0001562088-25-000042 | 10-K | XBRL Viewer

STOCK-BASED COMPENSATION - Schedule of Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Restricted stock units
Beginning balance (in shares)	1,802	2,027
Granted (in shares)	719
Released (in shares)	(821)
Forfeited (in shares)	(123)
Ending balance (in shares)	1,802
Weighted- average grant date fair value per share
Beginning balance (in usd per share)	$ 106.32
Granted (in usd per share)	199.82
Released (in usd per share)	103.81
Forfeited (in usd per share)	118.58
Ending balance (in usd per share)	$ 143.96

REVENUE - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 748,024	$ 531,109	$ 369,495
Subscription
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	607,531	404,684	273,507
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	140,493	126,425	95,988
Advertising
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	54,907	49,858	44,731
Duolingo English Test
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	45,640	41,212	32,718
In-App Purchases
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	38,653	34,673	17,914
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 1,293	$ 682	$ 625

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

REVENUE - Narrative (Details)	12 Months Ended
REVENUE - Narrative (Details)	Dec. 31, 2024 revenueSource user	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Number of sources of revenue \| revenueSource	4
Number of users \| user	6
Number of hours to make certification decision (less than)	48 hours
Number of days to take exam	21 days
Expiration period to take exams (in years)	1 year
Maximum
Disaggregation of Revenue [Line Items]
Subscription period (in years)	1 year
Revenue from Contract with Customer Benchmark \| Geographic Concentration Risk \| United States
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	42.00%	45.00%	46.00%
Apple \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	60.80%	58.50%	54.20%
Google \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	23.40%	25.60%	28.10%
Stripe \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	11.70%	12.10%

ACQUISITIONS

12 Months Ended

Dec. 31, 2024

Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]

ACQUISITIONS

During July 2024, the Company completed two acquisitions which brought new designer, illustration, animation, and engineering talent to Duolingo’s existing teams in addition to developed technology. The total aggregate consideration was $7,500, of which $7,100 represents the purchase price allocated to the fair value of the acquired assets and assumed liabilities, as detailed below. Of this, $6,600 was paid in cash upon closing, and $500 is being held back until certain post-acquisition conditions are satisfied. This $500 is recorded as a Current liability in the Consolidated Balance Sheet. The remaining $400 of the total aggregate consideration is contingent on one year of continued service of certain employees, and will be expensed over the period within General and administrative in the Consolidated Statements of Operations and Comprehensive Income (Loss). During 2024, the Company incurred $736 of acquisition costs related to due diligence and valuation, which are included in General and administrative expense within the Consolidated Statements of Operations and Comprehensive Income (Loss).

We finalized the valuation of assets acquired and liabilities assumed for the acquisitions during the year ended December 31, 2024. We did not record any measurement period adjustments during the year ended December 31, 2024. The following table summarizes the Company’s allocation of the purchase consideration based on the fair value of assets acquired and liabilities assumed at the acquisition dates:


(In thousands)	July 2024
Cash and cash equivalents	$	5
Other current assets acquired	37
Intangible assets, net
Technology	1,007
Goodwill	6,488
Other liabilities assumed	(437)
Total purchase price	$	7,100

Goodwill is attributable to the assembled workforce, future technologies and general going concern arising from the acquisitions. $3,600 of the goodwill recognized is expected to be deductible for income tax purposes.

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 785,791	$ 747,610
Short-term investments	91,854	0
Accounts receivable	128,923	88,975
Deferred cost of revenues	80,162	53,931
Prepaid expenses and other current assets	14,858	7,282
Total current assets	1,101,588	897,798
Operating lease right-of-use assets	47,495	19,103
Intangible assets, net	19,899	15,995
Long-term investments	98,292	0
Property and equipment, net	18,943	11,792
Goodwill	10,538	4,050
Restricted cash	2,735	2,735
Deferred tax assets, net	675	766
Other assets	1,563	1,718
Total assets	1,301,728	953,957
Current liabilities
Deferred revenues	372,884	249,192
Accounts payable	6,381	2,447
Income tax payable	6,591	792
Accrued expenses and other current liabilities	36,375	24,931
Total current liabilities	422,231	277,362
Long-term obligation under operating leases	54,656	21,094
Deferred tax liabilities, net	291	0
Total liabilities	477,178	298,456
Commitments and contingencies (Note 11)
Stockholders’ equity
Class A common stock, $0.0001 par value; 2,000,000 shares authorized as of December 31, 2024 and December 31, 2023; 38,730 and 36,311 issued and outstanding at December 31, 2024 and December 31, 2023, respectively Class B common stock, $0.0001 par value; 30,000 shares authorized as of December 31, 2024 and December 31, 2023; 6,206 and 6,215 issued and outstanding at December 31, 2024 and December 31, 2023, respectively	4	4
Additional paid-in capital	950,393	869,918
Accumulated deficit	(125,847)	(214,421)
Total stockholders’ equity	824,550	655,501
Total liabilities and stockholders' equity	$ 1,301,728	$ 953,957

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net income (loss)	$ 88,574,000	$ 16,067,000	$ (59,574,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	10,854,000	7,095,000	4,870,000
Stock-based compensation expense	110,477,000	95,221,000	73,820,000
Accretion on marketable securities, net	(551,000)	0	0
Gain on sale of capitalized software	0	(100,000)	0
Loss on disposal of leasehold improvements	0	433,000	0
Impairment of capitalized software	238,000	0	0
Changes in assets and liabilities:
Deferred revenue	123,692,000	91,642,000	59,283,000
Accounts receivable	(39,917,000)	(42,247,000)	(13,565,000)
Deferred cost of revenues	(26,231,000)	(18,890,000)	(10,822,000)
Prepaid expenses and other current assets	(7,570,000)	(48,000)	(1,415,000)
Accounts payable	3,934,000	1,261,000	(6,655,000)
Accrued expenses and other current liabilities	16,850,000	3,444,000	8,720,000
Noncurrent assets and liabilities	5,163,000	(264,000)	(1,006,000)
Net cash provided by operating activities	285,513,000	153,614,000	53,656,000
Cash flows from investing activities:
Purchases of investments	(193,300,000)	0	0
Maturities of investments	3,705,000	0	0
Capitalized software expense and purchases of intangible assets	(9,024,000)	(10,493,000)	(4,562,000)
Purchase of property and equipment	(12,116,000)	(3,191,000)	(5,562,000)
Proceeds from sale of capitalized software	0	100,000	0
Acquisitions of companies, net of $5 cash acquired	(6,595,000)	0	(4,050,000)
Net cash used for investing activities	(217,330,000)	(13,584,000)	(14,174,000)
Cash flows from financing activities:
Proceeds from exercise of stock options	19,356,000	13,617,000	14,776,000
Taxes paid related to net-share settlement of share-based compensation awards	(49,358,000)	(11,482,000)	0
Net cash (used for) provided by financing activities	(30,002,000)	2,135,000	14,776,000
Net increase in cash, cash equivalents and restricted cash	38,181,000	142,165,000	54,258,000
Cash, cash equivalents and restricted cash - Beginning of period	750,345,000	608,180,000	553,922,000
Cash, cash equivalents and restricted cash - End of period	788,526,000	750,345,000	608,180,000
Supplemental disclosure of cash flow information:
Cash paid for income taxes	7,620,000	2,320,000	615,000
Supplemental disclosure of noncash investing activities:
Capitalized software and purchases of intangible assets included in Current liabilities	0	0	1,121,000
Property and equipment included in Current liabilities	0	165,000	166,000
Landlord incentive included in Prepaid expenses and other current assets	0	0	2,148,000
Right of use assets obtained in exchange for new operating lease liabilities	33,039,000	0	909,000
Right of use assets disposed or adjusted modifying operating leases liabilities	$ 1,303,000	$ 2,024,000	$ 0

REVENUE (Tables)

12 Months Ended

Dec. 31, 2024

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue


	Year Ended December 31,
(In thousands)		2024		2023		2022
Revenues:
Subscription		$	607,531	$	404,684	$	273,507
Other (1)		140,493		126,425		95,988
Total revenues		$	748,024	$	531,109	$	369,495

________________

(1) Other revenue is comprised of the below.


	Year Ended December 31,
(In thousands)		2024		2023		2022
Advertising		$	54,907	$	49,858	$	44,731
Duolingo English Test		45,640		41,212		32,718
In-App Purchases		38,653		34,673		17,914
Other		1,293		682		625
Total other revenue		$	140,493	$	126,425	$	95,988

Schedule of Revenue by Geographic Areas

Information regarding geography of revenues is based upon the location where the users are located or, in the case of the Duolingo English Test, where the tests are taken:


	Year Ended December 31,
	2024		2023		2022
United States	$	311,539	$	238,759	$	168,320

Rest of World	436,485		292,350		201,175
Total	$	748,024	$	531,109	$	369,495

Schedule of Deferred Revenues

Changes in deferred revenues were as follows:


	Year Ended December 31,
(In thousands)	2024		2023
Beginning balance—January 1	$	249,192	$	157,550
Amount from beginning balance recognized into revenue	(248,667)		(157,550)
Recognition of deferred revenue	(402,937)		(287,429)
Deferral of revenue	775,296		536,621
Ending balance—December 31	$	372,884	$	249,192

EARNINGS (LOSS) PER SHARE - Narrative (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2024 vote	Dec. 31, 2022 shares
Founder awards where performance has been met
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Founder awards where performance not met (in shares) \| shares		1,620
Common Class A
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Voting rights, per share	1
Common Class B
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Voting rights, per share	20

COMMITMENTS AND CONTINGENCIES	12 Months Ended
COMMITMENTS AND CONTINGENCIES	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Proceedings— From time to time, the Company may become involved in various legal proceedings in the ordinary course of its business and may be subject to third-party infringement claims. The outcome of any such claims or proceedings, regardless of the merits, is inherently uncertain. The Company is not currently party to any material legal proceedings. Related Parties— The Company has determined that there were no transactions with related parties as of or during the years ended December 31, 2024, 2023 and 2022. Letters of Credit— The Company has a standby letter of credit obtained in connection with an operating lease. This letter of credit acts as security for the faithful performance by us of all terms, covenants and conditions of the lease agreement. The amount of the letter of credit is equal to six months rent of $442, totaling $2,656. The cash collateral for the letter of credit has been recognized as restricted cash in the Consolidated Balance Sheet and is equivalent to 103% of the letter of credit and totaled $2,735.

LEASES - Narrative (Details) $ in Thousands	Jun. 30, 2025 ft²	Dec. 31, 2024 USD ($)	May 31, 2024 ft²	Mar. 31, 2024 USD ($) ft²	Feb. 29, 2024 ft²	Dec. 31, 2023 USD ($)	Dec. 18, 2023 ft²
Lessee, Lease, Description [Line Items]
Renewal term (in years)		5 years
Obligations under current leases \| $		$ 2,581				$ 3,944
Operating lease, liability, current, statement of financial position, [extensible enumeration]		Accrued expenses and other current liabilities				Accrued expenses and other current liabilities
Long-term obligation under operating leases \| $		$ 54,656				$ 21,094
New York, New York
Lessee, Lease, Description [Line Items]
Area of office building							85,666
Seattle, Washington
Lessee, Lease, Description [Line Items]
Area of office building					7,940
Lease term (in months)					63 months
Pittsburgh, Pennsylvania
Lessee, Lease, Description [Line Items]
Leased square footage				110,008
Cost related to improvement to the premise \| $				$ 6,800
Pittsburgh, Pennsylvania \| Forecast
Lessee, Lease, Description [Line Items]
Area of office building	148,266
Beijing, China
Lessee, Lease, Description [Line Items]
Area of office building			16,314,000
Lease term (in months)			39 months

ACQUISITIONS (Tables)

12 Months Ended

Dec. 31, 2024

Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

The following table summarizes the Company’s allocation of the purchase consideration based on the fair value of assets acquired and liabilities assumed at the acquisition dates:


(In thousands)	July 2024
Cash and cash equivalents	$	5
Other current assets acquired	37
Intangible assets, net
Technology	1,007
Goodwill	6,488
Other liabilities assumed	(437)
Total purchase price	$	7,100

EARNINGS (LOSS) PER SHARE - Schedule of Antidilutive Securities (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2022 shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share (in shares)	6,626
Stock options outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share (in shares)	4,410
RSUs outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share (in shares)	2,036
Founder awards where performance has been met
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share (in shares)	180

REVENUE - Schedule of Revenue by Geographic Areas (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 748,024	$ 531,109	$ 369,495
United States
Disaggregation of Revenue [Line Items]
Revenues	311,539	238,759	168,320
Rest of World
Disaggregation of Revenue [Line Items]
Revenues	$ 436,485	$ 292,350	$ 201,175

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

+ References

+ Details

STOCK-BASED COMPENSATION - Schedule of Weighted Average Pricing Model (Details) - Founder awards where performance has been met	Jun. 28, 2021 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.48%
Expected life	9 years 11 months 23 days
Expected volatility	51.67%
Dividend yield	0.00%
Fair value of common stock (in usd per share)	$ 95.00

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

INCOME TAXES - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Expected income tax expense at federal statutory rate	21.00%	21.00%	21.00%
State taxes, net of Federal income tax effect	(3.80%)	(35.10%)	6.70%
Section 162(m) limitation	58.10%	56.50%	(15.20%)
Equity compensation	(97.90%)	(208.40%)	28.40%
Meals and entertainment	1.20%	5.60%	(1.20%)
Foreign-Derived Intangible Income deduction	(13.50%)	(13.40%)	0.00%
Other permanent adjustments	1.80%	2.20%	0.30%
Research and development credit	(23.50%)	(76.40%)	11.70%
Valuation allowance	70.00%	257.60%	(53.30%)
Effective income tax rate	13.40%	9.60%	(1.60%)

INTANGIBLE ASSETS AND GOODWILL - Schedule of Intangible Assets, Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2024 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2025	$ 8,493
2026	6,991
2027	3,750
2028	234
2029	157
Thereafter	157
Total estimated future amortization expense	$ 19,782

INCOME TAXES - Income Before Income Tax, Domestic and Foreign (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Domestic	$ 97,051	$ 16,501	$ (60,099)
Foreign	5,255	1,276	1,463
Income before income taxes	$ 102,306	$ 17,777	$ (58,636)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Accounting Principles—The Consolidated Financial Statements and accompanying notes are prepared in accordance with GAAP.

Use of Estimates—The preparation of Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying notes. Significant estimates and assumptions reflected in the Consolidated Financial Statements include, but are not limited to, useful lives of property and equipment, valuation of deferred tax assets and liabilities, stock-based compensation, operating lease right-of-use assets and liabilities, capitalization of internally developed software and associated useful lives and contingent liabilities, fair value of investments and valuation of goodwill and intangible assets from acquisitions. Actual results may differ materially from such estimates. Management believes that the estimates, and judgments upon which they rely, are reasonable based upon information available to them at the time that these estimates and judgments are made. To the extent that there are material differences between these estimates and actual results, the Company’s Consolidated Financial Statements will be affected.

Revenue Recognition—The Company has four predominant sources of revenue; time-based subscriptions, in-app advertising placement by third parties, the Duolingo English Test, and In-App Purchases. See Note 5, Revenue, for further discussion.

Deferred Revenues—Revenue is recognized over the life of the subscription, or in the case of Duolingo English Test, revenue is recognized when the test is proctored. The Company classifies deferred revenue as a short-term liability on the consolidated balance sheets as the longest subscription plan is for twelve months, and Duolingo English Test purchases must be taken within 21 days.

Cost of Revenues—Cost of revenue predominantly consists of third-party payment processing fees charged by various distribution channel and hosting fees. To a much lesser extent, includes wages and stock-based compensation for certain employees in the capacity of customer support, amortization of revenue generating capitalized software, and depreciation of certain property and equipment.

Deferred Cost of Revenues—Deferred cost of revenue includes third-party payment processing fees amortized over the subscription terms in proportion to the revenue recognized. In situations where fees are charged for subscriptions that exceed one month, costs are deferred and recognized over the life of the subscription and are classified as a current asset. The Company classifies deferred cost of revenue as a short-term asset on the Company’s consolidated balance sheets as the longest subscription plan is for twelve months.

Cash and Cash Equivalents—Cash consists primarily of cash on hand and bank deposits. Cash equivalents consist primarily of money market accounts with maturities of three months or less at the date of acquisition and are stated at cost, which approximates fair value. The Company maintains cash deposits with financial institutions that may exceed federally insured limits at times.

Investments —Investments consist primarily of corporate debt securities, U.S. Treasury securities, certificates of deposit, and commercial paper. Management determines the appropriate classification of investments at the time of purchase based upon management’s intent with regard to such investments. The Company’s investments are classified as held-to-maturity at the time of purchase, and such classifications are reevaluated as of each balance sheet date. All highly liquid investments with an original maturity of 90 days or less when purchased are considered to be cash equivalents. Investments with remaining contractual maturities of one year or less from the balance sheet date, which are not considered cash equivalents, are classified as short-term investments, and those with remaining contractual maturities greater than one year from the balance sheet date are classified as long-term investments. All investments are recorded at amortized cost. Realized gains and losses on sales and maturities of investments are determined based on the specific identification method and are recognized in the Consolidated Statements of Operations and Comprehensive Income (Loss).

We perform periodic evaluations to determine whether any declines in the fair value of investments below cost are other-than-temporary. The evaluation consists of qualitative and quantitative factors regarding the severity and duration of the unrealized loss, as well as the Company’s ability and intent to hold the investments until a forecasted recovery occurs. The impairments are considered to be other-than-temporary if they are related to deterioration in credit risk or if it is likely that the underlying securities will be sold or mature prior to a full recovery of their cost basis. Other-than-temporary fair value impairments, if any, are determined based on the specific identification method and are reported in Other (expense) income, net in the Consolidated Statements of Operations and Comprehensive Income (Loss)

Restricted Cash—Restricted cash consists of a collateralized letter of credit established in connection with a lease agreement for the Company’s Sub-Sublease in New York, which was signed in December 2023. Restricted cash is included in non-current assets for leases that expire in more than one year from the balance sheet date.

Accounts Receivable—Accounts receivables are reported on the consolidated balance sheets at the outstanding principal amount adjusted for any allowance for credit losses and any charge offs. The Company provides an allowance for credit losses to reduce trade receivables to their estimated net

realizable value equal to the amount that is expected to be collected. This allowance is estimated based on historical collection experience, the aging of receivables, specific current and expected future macro-economic and market conditions, and assessments of the current creditworthiness and economic status of customers. The Company considers a receivable delinquent if it is unpaid after the term of the related invoice has expired. Balances that are still outstanding after management has used reasonable collection efforts are written off. The Company reviews its allowance for credit losses on a quarterly basis. As of December 31, 2024 and 2023, the Company has not recorded a reserve given the Company’s lack of historical write offs.

Property and Equipment—Property and equipment is stated at cost, less accumulated depreciation. Depreciation is computed on the straight-line method.


Asset Class			Estimated Useful Life
Furniture, fixtures and equipment			4 to 6 years
Leasehold improvements			5 to 10 years

Leasehold improvements are amortized over the lesser of the life of the lease or the estimated useful life of the leasehold improvements. Costs related to maintenance and repairs that do not extend the assets’ useful life are expensed as incurred.

Acquisitions—The Company uses the acquisition method of accounting for business combination transactions, and, accordingly, recognizes the fair values of assets acquired and liabilities assumed in the Company’s Consolidated Financial Statements. The excess of the fair value of purchase consideration over the values of these identifiable assets and liabilities is recorded as goodwill. Transaction costs related to the acquisition of the acquired company are expensed as incurred. The allocation of fair values may be subject to adjustment after the initial allocation for up to a one-year period as more information becomes available relative to the fair values as of the acquisition date. The Consolidated Financial Statements include the results of operations of any acquired company since the acquisition date.

Goodwill—The Company recognizes the excess of the purchase price over the fair value of identifiable net assets acquired at the acquisition date as goodwill. Goodwill is not amortized but is reviewed for impairment annually and more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying value. The Company will review goodwill for impairment annually on October 1st of each fiscal year or whenever events or changes in circumstances indicate that an impairment may exist. The Company will first perform a qualitative assessment to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying value. If the reporting unit does not pass the qualitative assessment, then the reporting unit’s carrying value is compared to its fair value. If the fair value of the reporting unit is greater than the reporting unit’s carrying value, then the carrying value of the reporting unit is deemed to be recoverable. If the carrying value of the reporting unit is greater than the reporting unit’s fair value, goodwill is impaired and written down to the reporting unit’s fair value.

Intangible Assets—The majority of the Company’s intangible assets is capitalized software, with minimal acquired technology and other intangible assets during the years ended December 31, 2024 and 2023. The Company develops software for internal use and capitalizes the software development costs incurred during the application development stage. Costs incurred prior to and after the application development stage are charged to expense. When the software is ready for its intended use, capitalization ceases and such costs are amortized on a straight-line basis over the estimated life, which is generally three years. Relatively minor upgrades, enhancements and maintenance to the platform are expensed as incurred.

Income Taxes—The Company provides for income taxes in accordance with the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the carrying amounts of existing assets and liabilities for financial reporting and for income tax reporting. The deferred tax asset or liability represents the future tax return consequences of those difference, which will either be taxable or deductible when the assets and liabilities are recovered or settled. A valuation allowance is established for any deferred tax asset for which it is determined that it is more likely than not that some or all of the deferred tax assets will not be realized. The Company limits the deferred tax assets recognized related to certain officers’ compensation to amounts that it estimates will be deductible in future periods based upon Internal Revenue Code (“IRC”) Section 162(m).

The Company utilizes a two-step approach to recognizing and measuring uncertain tax positions accounted for in accordance with the asset and liability method. The first step is to evaluate the tax position for recognition by determining whether evidence indicates that it is more likely than not that a position will be sustained if examined by a taxing authority.

The second step is to measure the tax benefit as the largest amount that is 50% likely of being realized upon settlement with a tax authority. There were no amounts recorded at December 31, 2024 and December 31, 2023 related to uncertain tax positions.

Foreign Currency—The functional currency of the Company and its subsidiaries is the U.S. dollar. Transactions denominated in currencies other than the functional currency are translated into the functional currency at the exchange rates prevailing at the dates of the transaction. Monetary assets and liabilities denominated in foreign currencies are translated using the exchange rate prevailing at the balance sheet date. Non-monetary assets and liabilities are translated using the historical rate on the date of the transaction. All exchange gains or losses arising from translation of these foreign currency transactions are included in net loss for the year. The Company has not, to the date of these Consolidated Financial Statements, entered into derivative instruments to offset the impact of foreign currency fluctuations.

Fair Value of Financial Instruments—The Company accounts for certain assets and liabilities at fair value in accordance with the accounting guidance applicable to fair value measurements and disclosures. The carrying values of cash, cash equivalents, accounts receivable, accounts payable, and accrued expenses are deemed to be reasonable estimates of their fair values because of their short-term nature.

Research and Development Costs—Research and development expenses are incurred as the Company maintains and enhances its software and evaluates and develops other potential applications. Such expenses include compensation of engineering, product design and testing personnel, including stock-based compensation, materials, travel and direct costs associated with the design and required testing of our platform and depreciation of certain property and equipment.

Sales and Marketing—Sales and marketing expenses are expensed as incurred and consists primarily of new user acquisition, brand marketing, digital and social media content, and employee-related compensation, including stock-based compensation, for personnel engaged in sales and marketing functions, amortization of non-revenue generating capitalized software used to promote Duolingo and depreciation of certain property and equipment. Advertising costs were approximately $62,373, $52,969 and $48,111 for the years ended December 31, 2024, 2023 and 2022, respectively.

General and Administrative—General and administrative expense primarily consists of employee-related compensation (including stock-based compensation) for management and administrative functions, including our finance and accounting, legal, and people teams. General and administrative expense also includes certain professional services fees, general corporate and director and officer

insurance, facilities costs, and other general overhead costs that support our operations, and depreciation of certain property and equipment.

Concentration of Credit Risk—The Company’s concentration of credit risk relates to financial institutions holding the Company’s cash and cash equivalents and platforms with significant accounts receivable balances and revenue transactions.

The Company maintains cash deposits with financial institutions that may exceed federally insured limits at times. Management believes that the financial institutions that hold the Company’s deposits are financially credit worthy and, accordingly, minimal credit risk exists with respect to those balances.

The majority of our revenue comes through our subscriptions and advertising streams and payments are made to Duolingo through service providers. The top two service providers, Apple and Google, accounted for 64.7% and 21.2% of total Accounts receivable as of December 31, 2024, respectively. The top three service providers, Apple, Google and Stripe, accounted for 65.2%, 20.7% and 10.7% of total Accounts receivable as of December 31, 2023, respectively.

Stock-Based Compensation—The Company accounts for equity-based compensation using the fair value method as set forth in the ASC 718, Compensation—Stock Compensation, which requires the measurement and recognition of compensation expense for all stock-based payment awards based on estimated fair values. This method requires companies to estimate the fair value of stock-based compensation on the date of grant using an option pricing model. The Company estimates the fair value of each equity-based payment award on the date of grant using the Black-Scholes pricing model.

The Black-Scholes model determines the fair value of equity-based payment awards based on the fair value of the underlying common stock on the date of grant and requires the use of estimates and assumptions, including the fair value of the Company’s common stock, exercise price of the stock option, expected volatility, expected life, risk-free interest rate and dividend rate. The Company estimates the expected volatility of its stock options by taking the average historical volatility of a group of comparable publicly traded companies over a period equal to the expected life of the options; it is not practical for the Company to estimate its own volatility due to the lack of historical prices. The expected term of the options is determined in accordance with existing equity agreements as the underlying options are assumed to be exercised upon the passage of time. The risk-free interest rate is the estimated average interest rate based on U.S. Treasury zero-coupon notes with terms consistent with the expected life of the awards. The expected dividend yield is zero as the Company does not anticipate paying any recurring cash dividends in the foreseeable future. The Company accounts for forfeitures as they occur.

Restricted Stock Units (RSUs)

The Company began to grant RSUs in November 2020. The fair value of RSUs is estimated based on the fair value of the Company’s common stock on the date of grant. Generally, the service-based vesting condition for the majority of these awards is satisfied over four years.

Performance-based RSUs

In June 2021, the Company granted 1,800 (one million eight-hundred thousand) performance-based RSUs to the Company’s founders (“Founder Awards”). The Founder Awards are divided into ten equal tranches with each tranche becoming eligible to vest upon achievement of the specified stock-price hurdles. The Founder Awards vest upon the satisfaction of both a service-based condition and a performance-based condition and generally are settled one year after vesting. The service-based condition is satisfied as to 25% of the Founder Awards on each anniversary of the completion of the IPO, subject to the continuous service of the founders through the applicable date. The fair value of the

Founder Awards is determined using a Monte Carlo simulation model. The associated stock-based compensation is recorded over the derived service period, using the accelerated attribution method. If the stock-price hurdles are met sooner than the requisite service period, the stock-based compensation expense will be adjusted to prospectively recognize the remaining expense over the remaining derived service period. Provided that the founders continue to provide services to us, stock-based compensation expense is recognized over the derived service period, regardless of whether the stock-price hurdles are achieved. The first and second tranches were met during the year ended December 31, 2021. The third and fourth tranches were met during the year ended December 31, 2023. The fifth and sixth tranches were met during the year ended December 31, 2024. The Company recognized $19,799, $26,622 and $30,997 of stock-based compensation expense related to these awards, during the years ended December 31, 2024, 2023 and 2022, respectively, which is included within General and administrative in the Consolidated Statements of Operations and Comprehensive Income (Loss).

Contingencies—The Company records accruals for contingencies and legal proceedings expected to be incurred in connection with a loss contingency when it is probable that a liability has been incurred and the amount can be reasonably estimated.

If a loss contingency is not probable, but is reasonably possible, or is probable but cannot be estimated, the nature of the contingent liability, together with an estimate of the range of possible loss, would be disclosed.

Segment—The Company operates as a single operating segment and derives revenues from customers through time-based subscriptions, in-app advertising placement by third parties, the Duolingo English Test, and In-App Purchases. The Chief Executive Officer, as the chief operating decision maker, evaluates the Company’s performance and allocates resources based on consolidated net income, as presented in the income statement, supplemented by disaggregated revenue details. Significant segment expenses are those that are presented on the Consolidated Statements of Operations and Comprehensive Income (Loss). The measure of segment assets is reported on the balance sheet as total consolidated assets. Accordingly, the Company has determined that it has a single reportable segment and operating segment structure, and operates as one reporting unit.

Leases—The Company accounts for leases in accordance with ASC 842, Leases, which requires virtually all leases, other than leases that meet the definition of a short-term lease, to be recorded on the balance sheet with a right-of-use (“ROU”) asset and corresponding lease liability. ROU assets are periodically reviewed for impairment whenever events or changes in circumstances arise. During the years ended December 31, 2024, 2023 and 2022, the Company incurred no impairment charges on ROU assets.

On the lease commencement date, each lease is classified as either finance or operating, depending on certain criteria. The Company determined that it only has operating leases as none of the criteria for finance lease classification were met. Operating lease expense is recognized on a straight-line basis on the Consolidated Statements of Operations and Comprehensive Income (Loss) in General and administrative expenses. On the Consolidated Statements of Changes in Cash Flows, payments for operating leases, are included in operating activities. As an accounting policy election, the Company has elected to not separate lease and non-lease components for all asset classes and made an accounting policy election for short-term leases which does not require the capitalization of leases with terms of 12 months or less at lease commencement. The discount rate utilized in calculating the lease liability is the rate implicit in the lease, if known; otherwise, the incremental borrowing rate (“IBR”) for the expected lease term is used. The Company’s IBR approximates the rate the Company would have to pay, on a collateralized basis, to borrow an amount equal to the lease payments under similar terms.

Impairment of long-lived assets— The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If the sum of the estimated undiscounted future cash flows expected to result from the use and eventual disposition of an asset is less than the carrying amount of the asset, an impairment loss is recognized. Measurement of an impairment loss is based on the fair value of the asset. The Company recorded an impairment of capitalized software of $238 for the year ended December 31, 2024, and no impairment during the years ended December 31, 2023 and 2022, which represents an impairment to write-off the capitalization of an internal-use software project prior to being launched to the user base.

Allowance for Credit Losses—The Company evaluates its cash equivalents, accounts receivable and held-to-maturity marketable securities financial assets for expected credit losses. Expected credit losses represent the portion of the amortized cost basis of a financial asset that an entity does not expect to collect. An allowance for expected credit losses is meant to reflect a risk of loss even if remote, irrespective of the expectation of collection from a particular issuer or debt security. The Company has not historically experienced any credit losses on any of its financial assets.

With respect to cash equivalents and accounts receivable, given consideration of their short maturity, lack of historical losses and the current environment, the Company concluded there is generally no expected credit losses for these financial assets. With respect to held-to-maturity marketable securities which are comprised of debt securities, the Company evaluates expected credit losses on a pooled basis based on issuer-type which have similar credit risk characteristics. The allowance for credit losses is immaterial for all periods presented.

Recently Issued Pronouncements Not Yet Adopted

There are no recently issued accounting pronouncements that the Company has not yet adopted that they believe are applicable or would have a material impact on the financial statements of the Company.

In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740), which includes improvements to income tax disclosures. The standard is effective for public entities in fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company does not expect the adoption of the new guidance will have a material impact on the Company’s consolidated financial statements and related disclosures.

In November 2024, the FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. The amendment requires new financial statement disclosures to provide disaggregated information for certain types of expenses, including employee compensation, depreciation, and amortization in commonly presented expense captions such as cost of revenue, sales and marketing, and general and administrative expenses. The amendments in this ASU are effective for annual reporting periods beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. The Company is in the process of evaluating the effect that the adoption of these standards will have on its consolidated financial statements.

Recently Adopted Accounting Pronouncements

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280), which improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. The standard is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company adopted this guidance on January 1, 2024. Refer to our discussion above under “Segment” within this footnote.

INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 4,491	$ 15,533
Stock-based compensation	4,755	5,207
Research and development credits	61,198	38,146
Lease liability	13,004	5,739
Section 174 research and development capitalization	190,768	102,055
Marketing and advertising	674	766
Sales tax / Value added tax ("VAT") reserve	560	397
Other deferred tax assets	70	65
Valuation allowance	(256,728)	(156,870)	$ (108,504)
Total deferred tax assets	18,792	11,038
ROU asset	(10,757)	(4,354)
Property and equipment	(2,885)	(2,164)
Capitalized software	(4,444)	(3,716)
Other deferred tax liabilities	(322)	(38)
Total deferred tax liabilities	(18,408)	(10,272)
Net deferred taxes	$ 384	$ 766

EMPLOYEE BENEFIT PLAN	12 Months Ended
EMPLOYEE BENEFIT PLAN	Dec. 31, 2024
Postemployment Benefits [Abstract]
EMPLOYEE BENEFIT PLAN	EMPLOYEE BENEFIT PLAN The Company sponsors a profit sharing plan with a 401(k) feature, the Duolingo Retirement Plan (the “Plan”), for eligible employees. The current Plan, effective January 1, 2021, provides for Company safe harbor matching contributions of 100% of the first 4% of the employees’ elective deferrals and 50% of the next 2%, with vesting starting upon the first day of employment. The Company also has the option to make discretionary matching or profit sharing contributions. The Company made safe harbor matching contributions of approximately $6,965, $5,908 and $4,624 during the years ended December 31, 2024, 2023 and 2022 respectively. The Company did not make any discretionary matching or profit sharing contributions during the years ended December 31, 2024, 2023 and 2022.

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2021		38,272
Beginning balance at Dec. 31, 2021	$ 513,056	$ 4	$ 683,966	$ (170,914)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	73,820		73,820
Stock options exercised (in shares)		1,739
Stock options exercised	14,776		14,776
Release of restricted stock units (in shares)		350
Net (loss) income	(59,574)			(59,574)
Ending balance (in shares) at Dec. 31, 2022		40,361
Ending balance at Dec. 31, 2022	542,078	$ 4	772,562	(230,488)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	95,221		95,221
Release of performance stock units (in shares)		180
Taxes paid related to net-share settlement of share-based compensation awards (in shares)		(84)
Taxes paid related to net-share settlement of share-based compensation awards	(11,482)		(11,482)
Stock options exercised (in shares)		1,396
Stock options exercised	13,617		13,617
Release of restricted stock units (in shares)		673
Net (loss) income	16,067			16,067
Ending balance (in shares) at Dec. 31, 2023		42,526
Ending balance at Dec. 31, 2023	655,501	$ 4	869,918	(214,421)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	110,477		110,477
Release of performance stock units (in shares)		270
Taxes paid related to net-share settlement of share-based compensation awards (in shares)		(143)
Taxes paid related to net-share settlement of share-based compensation awards	$ (49,358)		(49,358)
Stock options exercised (in shares)	1,462	1,462
Stock options exercised	$ 19,356		19,356
Release of restricted stock units (in shares)		821
Net (loss) income	88,574			88,574
Ending balance (in shares) at Dec. 31, 2024		44,936
Ending balance at Dec. 31, 2024	$ 824,550	$ 4	$ 950,393	$ (125,847)

Insider Trading Arrangements	3 Months Ended	12 Months Ended
Insider Trading Arrangements	Dec. 31, 2024 shares	Dec. 31, 2024 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Natalie Glance [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On November 14, 2024, Natalie Glance, Chief Engineering Officer, entered into a 10b5-1 sales plan (the “Glance 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Exchange Act and providing for (i) the sale of the net number of shares of Class A common stock underlying 22,099 unvested restricted stock units received after giving effect to the number of shares automatically sold to satisfy tax withholding obligations on each applicable vesting date (such total number of shares covered under clause (i) is not determinable) and (ii) the sale of 14,855 shares of Class A common stock shares. The Glance 10b5-1 Sales Plan will remain in effect until the earlier of (1) December 31, 2025, (2) the date on which all trades set forth in the Glance 10b5-1 Sales Plan have been executed, or (3) such time as the Glance 10b5-1 Sales Plan is otherwise terminated according to its terms.
Name	Natalie Glance
Title	Chief Engineering Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	November 14, 2024
Expiration Date	December 31, 2025
Arrangement Duration	412 days
Gillian Munson [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On December 7, 2024, Gillian Munson, a member of our Board of Directors, entered into a 10b5-1 sales plan (the “Munson 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Exchange Act and providing for the potential exercise of vested stock options and the associated sale of up to 5,000 shares of the Company’s Class A common stock. The Munson 10b5-1 Sales Plan will remain in effect until the earlier of (1) August 14, 2025, (2) the date on which all trades set forth in the Munson 10b5-1 Sales Plan have been executed, or (3) such time as the Munson 10b5-1 Sales Plan is otherwise terminated according to its terms.
Name	Gillian Munson
Title	member of our Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 7, 2024
Expiration Date	August 14, 2025
Arrangement Duration	250 days
Aggregate Available	5,000	5,000
James Shelton [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On December 9, 2024, James Shelton, a member of our Board of Directors, entered into a 10b5-1 sales plan (the “Shelton 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Exchange Act and providing for (i) the potential exercise of vested stock options and the associated sale of up to 20,000 shares of the Company’s Class A common stock, and (ii) the sale of up to 895 shares of Class A common stock underlying unvested restricted stock units. The Shelton 10b5-1 Sales Plan will remain in effect until the earlier of (1) August 29, 2025, (2) the date on which all trades set forth in the Shelton 10b5-1 Sales Plan have been executed, or (3) such time as the Shelton 10b5-1 Sales Plan is otherwise terminated according to its terms.
Name	James Shelton
Title	member of our Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 9, 2024
Expiration Date	August 29, 2025
Arrangement Duration	263 days
Robert Meese [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On December 9, 2024, Robert Meese, Chief Business Officer, entered into a 10b5-1 sales plan (the “Meese 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Exchange Act and providing for (i) the sale of the net number of shares of Class A common stock underlying 3,543 restricted stock units received after giving effect to the number of shares automatically sold under the Meese 10b5-1 Sales Plan to satisfy tax withholding obligations on each applicable vesting date (such total number of shares covered under clause (i) is not determinable) and (ii) the sale of 18,080 shares of Class A common stock shares. The Meese 10b5-1 Sales Plan will remain in effect until the earlier of (1) December 31, 2025, (2) the date on which all trades set forth in the Meese 10b5-1 Sales Plan have been executed, or (3) such time as the Meese 10b5-1 Sales Plan is otherwise terminated according to its terms.
Name	Robert Meese
Title	Chief Business Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 9, 2024
Expiration Date	December 31, 2025
Arrangement Duration	387 days
Natalie Glance Trading Arrangement, Unvested Restricted Stock Units [Member] \| Natalie Glance [Member]
Trading Arrangements, by Individual
Aggregate Available	22,099	22,099
Natalie Glance Trading Arrangement, Common Stock [Member] \| Natalie Glance [Member]
Trading Arrangements, by Individual
Aggregate Available	14,855	14,855
James Shelton Trading Arrangement, Common Stock [Member] \| James Shelton [Member]
Trading Arrangements, by Individual
Aggregate Available	20,000	20,000
James Shelton Trading Arrangement, Common Stock Underlying Unvested Restricted Stock Units [Member] \| James Shelton [Member]
Trading Arrangements, by Individual
Aggregate Available	895	895
Robert Meese Trading Arrangement, Restricted Stock Units [Member] \| Robert Meese [Member]
Trading Arrangements, by Individual
Aggregate Available	3,543	3,543
Robert Meese Trading Arrangement, Common Stock [Member] \| Robert Meese [Member]
Trading Arrangements, by Individual
Aggregate Available	18,080	18,080

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Revenues	$ 748,024	$ 531,109	$ 369,495
Cost of revenues	203,645	142,105	99,431
Gross profit	544,379	389,004	270,064
Operating expenses:
Research and development	235,298	194,352	150,444
Sales and marketing	90,494	75,788	66,967
General and administrative	155,992	132,123	117,848
Total operating expenses	481,784	402,263	335,259
Income (loss) from operations	62,595	(13,259)	(65,195)
Other income	1,267	590	131
Other expense	(4,253)	(645)	(807)
Other (expense) income, net	(2,986)	(55)	(676)
Income (loss) before interest income and income taxes	59,609	(13,314)	(65,871)
Interest income	42,697	31,091	7,235
Income before income taxes	102,306	17,777	(58,636)
Provision for income taxes	13,732	1,710	938
Net income (loss)	88,574	16,067	(59,574)
Net comprehensive income (loss)	$ 88,574	$ 16,067	$ (59,574)
Net income (loss) per share attributable to Class A and Class B common stockholders, basic (in usd per share)	$ 2.04	$ 0.39	$ (1.51)
Net income (loss) per share attributable to Class A and Class B common stockholders, diluted (in usd per share)	$ 1.88	$ 0.35	$ (1.51)

LEASES

12 Months Ended

Dec. 31, 2024

Leases [Abstract]

LEASES

The Company has entered into various operating leases for its office space expiring between fiscal 2024 and 2036. Certain lease agreements contain an option for the Company to renew a lease for a term of up to five years. The Company considers these options, which may be elected at the Company’s sole discretion, in determining the lease term on a lease-by-lease basis.

On December 18, 2023, the Company entered into an Agreement of Sub-Sublease, with Spotify USA Inc., as Sub-Sublandlord for 85,666 square feet of office space in the building located at 4 World Trade Center, 150 Greenwich Street, New York, New York 10007 for use as additional office space. The term of the Sub-Sublease commenced on January 8, 2024 and will expire on April 29, 2034.

In February 2024, the Company signed a lease with Bullitt Center LLC for 7,940 square feet of office space in Seattle, Washington. The term of the lease is 63 months beginning on March 1, 2024 and expiring on May 31, 2029.

In March 2024, the Company entered into the First and Second Amendments (the “Amendments”) to the Office Lease Agreement with 5704 Penn Office, LLC (the "Landlord") for office space located at Liberty East (the “Premise”) at 141 South Saint Clair Street, Pittsburgh, Pennsylvania, which, among other things, increased the leased square footage by 110,008 square feet to a total of 148,266 square feet beginning when construction of the leasehold improvements commences in the first half of 2025, with an expiration date of April 30, 2036. Under the terms of the Amendments, the Landlord will provide the Company with an improvement allowance of up to approximately $6,800 for costs relating to the design, permitting, and construction of improvements to the Premise.

In May 2024, the Company signed a lease with Beijing Hengshi Huarong Holding Co., Ltd. for 16,314 square feet of office space in Beijing, China. The term of the lease is 39 months beginning on May 20, 2024 and expiring on July 15, 2027.

The following represents the components of lease cost for the year ended December 31, 2024 and 2023 along with supplemental disclosures of cash flow information, lease term and discount rate:


	Year Ended December 31,
		2024		2023		2022
Operating lease cost		$	9,982	$	7,459	$	7,076
Short term lease cost		83		48		125
Variable lease cost		468		252		63
Total lease cost		$	10,533	$	7,759	$	7,264

Cash paid for amounts included in the measurement of lease liabilities		$	5,727	$	7,512	$	5,168
Right-of-use assets obtained in exchange for new operating lease liabilities		$	33,039	$	—	$	909
Right of use assets disposed or adjusted, modifying operating leases liabilities		$	1,302	$	2,024	$	(1,586)


	December 31, 2024		December 31, 2023		December 31, 2022
Weighted-average remaining lease term	9 years		9 years		9 years
Weighted-average discount rate	7.16	%	7.38	%	6.92	%

Sublease income was immaterial for the years ended December 31, 2024, 2023 and 2022.

The following table reconciles future minimum undiscounted rental commitments for operating leases to operating lease liabilities recorded on the Consolidated Balance Sheet as of December 31, 2024:


Fiscal year
2025	$	4,185
2026	9,134
2027	9,505
2028	9,299
2029	9,492
Thereafter	38,989
Total undiscounted lease payments	$	80,604
Present value adjustment	(23,367)
Operating lease liabilities	$	57,237

Current lease liabilities of $2,581 and $3,944 are presented within Accrued expenses and other liabilities while non-current lease liabilities of $54,656 and $21,094 are presented within Long-term obligation under operating leases on the Consolidated Balance Sheets for the years ended December 31, 2024 and 2023, respectively.

LEASES - Schedule of Components of Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease cost	$ 9,982	$ 7,459	$ 7,076
Short term lease cost	83	48	125
Variable lease cost	468	252	63
Total lease cost	10,533	7,759	7,264
Cash paid for amounts included in the measurement of lease liabilities	5,727	7,512	5,168
Right-of-use assets obtained in exchange for new operating lease liabilities	33,039	0	909
Right of use assets disposed or adjusted, modifying operating leases liabilities	$ 1,302	$ 2,024	$ (1,586)
Weighted-average remaining lease term	9 years	9 years	9 years
Weighted-average discount rate	7.16%	7.38%	6.92%

INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
INCOME TAXES - Narrative (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Tax Credit Carryforward [Line Items]
Increase in valuation allowance	$ 99,858,000
Unrecognized tax benefits	0	$ 0	$ 0
General Business Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Business credits	61,198,000
State
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	$ 60,683,000

ACQUISITIONS - Narrative (Details)	1 Months Ended	12 Months Ended
ACQUISITIONS - Narrative (Details)	Jul. 31, 2024 USD ($) acquisition	Dec. 31, 2024 USD ($)
Business Acquisition [Line Items]
Measurement period adjustments		$ 0
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Number of businesses acquired \| acquisition	2
Total consideration	$ 7,500,000
Purchase price	7,100,000
Payments to acquire businesses	6,600,000
Current liability	500,000
Contingent consideration	$ 400,000
Continued service period (in years)	1 year
Acquisition costs		$ 736,000
Goodwill recognized is expected to be deductible for income tax	$ 3,600,000

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended
	Jan. 01, 2025 shares	Jul. 26, 2021 shares	Jun. 30, 2021 USD ($) tranche day $ / shares shares	Dec. 31, 2024 USD ($) shares	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) \| shares				0
Aggregate intrinsic value, exercised \| $				$ 365,484	$ 192,456	$ 140,884
Unrecognized compensation cost, options \| $				23
Unrecognized compensation cost \| $				239,161
Closing trading price, specified calendar day \| day			60
Compensation expense \| $				$ 110,477	95,221	73,820
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, weighted-average period of recognition (in years)				2 months
Number of options available for grant (in shares) \| shares				8,951,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)				4 years
Unrecognized compensation cost, weighted-average period of recognition (in years)				3 years
Unrecognized compensation expense, excluding options \| $				$ 239,138
Equity instruments other than options, grants in period (in shares) \| shares				719,000
Performance Based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, excluding options \| $				$ 16,936
Compensation expense \| $				$ 19,799	$ 26,622	$ 30,997
Performance Based RSUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award service period (in years)			3 years 6 months 29 days
Performance Based RSUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award service period (in years)			5 years 11 months 1 day
Performance Based RSUs \| Founders
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, excluding options \| $			$ 110,817
Equity instruments other than options, grants in period (in shares) \| shares			1,800,000
Settlement period after vesting (in years)			1 year
Award vesting percentage (in percent)			25.00%
Number of tranches \| tranche			10
Award service period (in years)			10 years
Performance Based RSUs \| Share-Based Payment Arrangement, Founders
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in usd per share) \| $ / shares			$ 61.56
2021 Plan \| Common Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares) \| shares		7,946,000
Share-based compensation, shares outstanding increase, maximum amount (in percent)		5.00%
2021 Plan \| Common Class A \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized (in shares) \| shares	2,247,000
Employee Stock Purchase Plan \| Common Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares) \| shares		1,119,000
Share-based compensation, shares outstanding increase, maximum amount (in percent)		1.00%
2011 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)				4 years
Share-based compensation, term of award (in years)				10 years
Granted (in shares) \| shares				0

ACQUISITIONS - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Jul. 31, 2024	Dec. 31, 2023
Business Acquisition [Line Items]
Goodwill	$ 10,538		$ 4,050
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Cash and cash equivalents		$ 5
Other current assets acquired		37
Technology		1,007
Goodwill		6,488
Other liabilities assumed		(437)
Total purchase price		$ 7,100

- Definition

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

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+ Details

Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	Dec. 31, 2024	Feb. 26, 2025	Jun. 28, 2024
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-40653
Entity Registrant Name	Duolingo, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-3055872
Entity Address, Address Line One	5900 Penn Avenue
Entity Address, City or Town	Pittsburgh
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	15206
City Area Code	(412)
Local Phone Number	567-6602
Title of 12(b) Security	Class A common stock, $0.0001 per share
Trading Symbol	DUOL
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction Flag	false
Entity Shell Company	false
Entity Public Float			$ 6,153,312,710
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement for its 2025 annual meeting of stockholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year ended December 31, 2024, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Entity Central Index Key	0001562088
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		39,044,190
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		6,198,612

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net income (loss) attributable to Class A and Class B common stockholders	$ 88,574	$ 16,067	$ (59,574)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) shares in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2021 shares	Dec. 31, 2024 USD ($) revenueSource tranche reporting_unit shares	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Concentration Risk [Line Items]
Number of sources of revenue \| revenueSource		4
Number of days to take exam		21 days
Advertising costs		$ 62,373,000	$ 52,969,000	$ 48,111,000
Compensation expense		$ 110,477,000	95,221,000	73,820,000
Number of reporting units \| reporting_unit		1
Impairment		$ 0	0	0
Impairment of capitalized software		$ 238,000	0	0
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income or Comprehensive Income [Extensible Enumeration]		Impairment of capitalized software
RSUs outstanding
Concentration Risk [Line Items]
Vesting period (in years)		4 years
Equity instruments other than options, grants in period (in shares) \| shares		719
Founder awards where performance has been met
Concentration Risk [Line Items]
Compensation expense		$ 19,799,000	$ 26,622,000	$ 30,997,000
Founder awards where performance has been met \| Founders
Concentration Risk [Line Items]
Equity instruments other than options, grants in period (in shares) \| shares	1,800
Number of tranches \| tranche		10
Apple \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk (in percent)		64.70%	65.20%
Google \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk (in percent)		21.20%	20.70%
Stripe \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk (in percent)			10.70%
Capitalized Software
Concentration Risk [Line Items]
Estimated useful life (in years)		3 years

LEASES - Schedule of Future Minimum Rental Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2024 USD ($)
Leases [Abstract]
2025	$ 4,185
2026	9,134
2027	9,505
2028	9,299
2029	9,492
Thereafter	38,989
Total undiscounted lease payments	80,604
Present value adjustment	(23,367)
Operating lease liabilities	$ 57,237

PROPERTY and EQUIPMENT, net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 35,353	$ 24,060
Less: accumulated depreciation	(16,410)	(12,268)
Total property and equipment, net	18,943	11,792
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	26,938	18,191
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 8,415	$ 5,869

FAIR VALUE (Tables)

12 Months Ended

Dec. 31, 2024

Fair Value Disclosures [Abstract]

Schedule of Net Unrealized Gains (Losses), and Fair Value by Major Security Type for Our Investments

The following table presents amortized cost, gross unrealized gains and losses, and fair value by major security type and balance sheet classification as of December 31, 2024 and December 31, 2023:


As of December 31, 2024
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Cash Equivalents		Short-Term Investments		Long-Term Investments
Cash	$	—	$	—	$	—	$	73,351	$	73,351	$	—	$	—

Level 1
Commercial paper	$	15,659	$	2	$	(1)	$	15,661	$	—	$	15,659	$	—
Money market funds	712,440		—		—		712,440		712,440		—		—
Subtotal	$	728,099	$	2	$	(1)	$	728,101	$	712,440	$	15,659	$	—

Level 2
Asset-backed securities	$	16,280	$	10	$	(1)	$	16,289	$	—	$	697	$	15,583
Certificates of deposit	11,521		—		(14)		11,507		—		11,521		—
Corporate debt securities	126,031		7		(494)		125,543		—		55,013		71,018
U.S. Treasury securities	19,255		2		(61)		19,195		—		8,964		10,291
Subtotal	$	173,087	$	19	$	(570)	$	172,534	$	—	$	76,195	$	96,892

Level 3
Investment in SAFE	$	—	$	—	$	—	$	1,400	$	—	$	—	$	1,400
Subtotal	$	—	$	—	$	—	$	1,400	$	—	$	—	$	1,400
Total	$	901,186	$	21	$	(571)	$	975,386	$	785,791	$	91,854	$	98,292


As of December 31, 2023
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Cash Equivalents		Short-Term Investments		Long-Term Investments
Cash	$	—	$	—	$	—	$	50,373	$	50,373	$	—	$	—

Level 1
Money market funds	$	697,237	$	—	$	—	$	697,237	$	697,237	$	—	$	—





Total	$	697,237	$	—	$	—	$	747,610	$	747,610	$	—	$	—

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Schedule of Income (Loss) Before Income Tax, Domestic and Foreign

For the years ended December 31, 2024, 2023 and 2022 income (loss) before income taxes included the following components:


	Year Ended December 31,
	2024		2023		2022
Domestic	$	97,051	$	16,501	$	(60,099)
Foreign	5,255		1,276		1,463
Total	$	102,306	$	17,777	$	(58,636)

Schedule of Effective Income Tax Rate Reconciliation

For the years ended December 31, 2024, 2023 and 2022 the Company recognized the following provision for income taxes:


	Year Ended December 31,
	2024		2023		2022
Current:
Federal	$	10,652	$	895	$	302
State	2,639		607		327
Foreign	284		341		524
Total	$	13,575	$	1,843	$	1,153

Deferred:
Federal	$	—	$	—	$	—
State	—		—		—
Foreign	157		(133)		(215)
Total	$	157	$	(133)	$	(215)

Total provision for income taxes	$	13,732	$	1,710	$	938

The provision for income taxes differs from the amounts computed by applying the federal statutory rate as follows for the years ended December 31, 2024, 2023 and 2022:


	2024		2023		2022
Expected income tax expense at federal statutory rate	21.0	%	21.0	%	21.0	%
State taxes, net of Federal income tax effect	(3.8)		(35.1)		6.7
Section 162(m) limitation	58.1		56.5		(15.2)
Equity compensation	(97.9)		(208.4)		28.4
Meals and entertainment	1.2		5.6		(1.2)
Foreign-Derived Intangible Income deduction	(13.5)		(13.4)		—
Other permanent adjustments	1.8		2.2		0.3
Research and development credit	(23.5)		(76.4)		11.7
Valuation allowance	70.0		257.6		(53.3)
Effective income tax rate	13.4	%	9.6	%	(1.6)	%

Schedule of Deferred Tax Assets and Liabilities

The Company has the following deferred tax assets (liabilities) as of December 31, 2024 and 2023:


	2024		2023
Net operating loss carryforwards	$	4,491	$	15,533
Stock-based compensation	4,755		5,207
Research and development credits	61,198		38,146
Lease liability	13,004		5,739
Section 174 research and development capitalization	190,768		102,055
Marketing and advertising	674		766
Sales tax / Value added tax ("VAT") reserve	560		397
Other deferred tax assets	70		65
Valuation allowance	(256,728)		(156,870)
Total deferred tax assets	18,792		11,038

ROU asset	(10,757)		(4,354)
Property and equipment	(2,885)		(2,164)
Capitalized software	(4,444)		(3,716)
Other deferred tax liabilities	(322)		(38)
Total deferred tax liabilities	(18,408)		(10,272)

Net deferred taxes	$	384	$	766

Schedule of Valuation Allowance

The following table represents the activity in our valuation allowance for the years ended December 31, 2024 and 2023:


	Year Ended December 31,
	2024		2023
Beginning balance—January 1	$	(156,870)	$	(108,504)
Valuation allowances established	(99,858)		(48,366)
Release of valuation allowances	—		—
Ending balance—December 31	$	(256,728)	$	(156,870)

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)
Statement of Cash Flows [Abstract]
Cash acquired during acquisition	$ 5

INTANGIBLE ASSETS AND GOODWILL (Tables)

12 Months Ended

Dec. 31, 2024

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets

Intangible assets consist of the following as of December 31, 2024 and December 31, 2023:


(In thousands)	December 31, 2024		December 31, 2023
Capitalized software	$	35,681	$	26,895
Acquired technology	1,007		—
Other intangible assets	117		117
Total intangible assets	36,805		27,012
Less: accumulated amortization	(16,906)		(11,017)
Intangible assets, net	$	19,899	$	15,995

Schedule of Intangible Assets Amortization Expense

Amortization expense is included within the following financial statement line items within the Company’s Consolidated Statements of Operations and Comprehensive Income (Loss).


	Year Ended December 31,
(In thousands)		2024		2023		2022
Cost of revenues		$	5,310	$	2,020	$	870
Sales and marketing		579		975		882
Total		$	5,889	$	2,995	$	1,752

Schedule of Intangible Assets, Future Amortization Expense

The estimated future amortization expense of capitalized software and acquired technology with definite lives as of December 31, 2024 was as follows:


(In thousands)	Amortization Expense
2025	$	8,493
2026	6,991
2027	3,750
2028	234
2029	157
Thereafter	157
Total estimated future amortization expense	$	19,782

Schedule of Goodwill

The following table represents the changes to goodwill during the twelve months ended December 31, 2024:


	Carrying amount
Balance as of December 31, 2023	$	4,050
Acquisitions	6,488
Balance as of December 31, 2024	$	10,538

- Definition

Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.

+ References

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-URI https://asc.fasb.org/1943274/2147482573/350-20-50-2

+ Details

INCOME TAXES

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

INCOME TAXES

For the years ended December 31, 2024, 2023 and 2022 income (loss) before income taxes included the following components:


	Year Ended December 31,
	2024		2023		2022
Domestic	$	97,051	$	16,501	$	(60,099)
Foreign	5,255		1,276		1,463
Total	$	102,306	$	17,777	$	(58,636)

For the years ended December 31, 2024, 2023 and 2022 the Company recognized the following provision for income taxes:


	Year Ended December 31,
	2024		2023		2022
Current:
Federal	$	10,652	$	895	$	302
State	2,639		607		327
Foreign	284		341		524
Total	$	13,575	$	1,843	$	1,153

Deferred:
Federal	$	—	$	—	$	—
State	—		—		—
Foreign	157		(133)		(215)
Total	$	157	$	(133)	$	(215)

Total provision for income taxes	$	13,732	$	1,710	$	938

The provision for income taxes differs from the amounts computed by applying the federal statutory rate as follows for the years ended December 31, 2024, 2023 and 2022:


	2024		2023		2022
Expected income tax expense at federal statutory rate	21.0	%	21.0	%	21.0	%
State taxes, net of Federal income tax effect	(3.8)		(35.1)		6.7
Section 162(m) limitation	58.1		56.5		(15.2)
Equity compensation	(97.9)		(208.4)		28.4
Meals and entertainment	1.2		5.6		(1.2)
Foreign-Derived Intangible Income deduction	(13.5)		(13.4)		—
Other permanent adjustments	1.8		2.2		0.3
Research and development credit	(23.5)		(76.4)		11.7
Valuation allowance	70.0		257.6		(53.3)
Effective income tax rate	13.4	%	9.6	%	(1.6)	%

The 2024 and 2023 effective tax rate differs from the statutory rate as a result of an increase in tax deductible stock-based compensation and the generation of research and development tax credits offset by an increase in the valuation allowance for the Company’s net deferred tax assets. For 2022, the

effective tax rate is less than the statutory rate primarily as a result of the valuation allowance for the Company’s net deferred tax assets.

The Company has the following deferred tax assets (liabilities) as of December 31, 2024 and 2023:


	2024		2023
Net operating loss carryforwards	$	4,491	$	15,533
Stock-based compensation	4,755		5,207
Research and development credits	61,198		38,146
Lease liability	13,004		5,739
Section 174 research and development capitalization	190,768		102,055
Marketing and advertising	674		766
Sales tax / Value added tax ("VAT") reserve	560		397
Other deferred tax assets	70		65
Valuation allowance	(256,728)		(156,870)
Total deferred tax assets	18,792		11,038

ROU asset	(10,757)		(4,354)
Property and equipment	(2,885)		(2,164)
Capitalized software	(4,444)		(3,716)
Other deferred tax liabilities	(322)		(38)
Total deferred tax liabilities	(18,408)		(10,272)

Net deferred taxes	$	384	$	766

The Company has provided a full valuation allowance for its U.S. federal and state net deferred tax asset as it is not more likely than not that the asset will be realized. The movement in valuation allowance of $99,858 is primarily related to the:

•increase to the deferred tax assets for the capitalization of research and development expenditures under Section 174, which was a change in tax law from the Tax Cuts and Job Acts of 2017, which went into effect in January 2022,

•an increase in the generation of research and development tax credits, and

•a reduction in the Company’s net operating losses.

The Company has a deferred tax asset with respect to its China subsidiary, against which no valuation allowance has been recorded.

Given the Company’s recent history of earnings, management believes that there is a reasonable possibility that, within the next twelve months, sufficient positive evidence may become available to allow management to reach a conclusion that a significant portion of the valuation allowance recorded against the deferred tax assets held will be reversed. The reversal would result in an income tax benefit for the quarterly and annual fiscal period in which the Company releases the valuation allowance. However, the exact timing and amount of the valuation allowance release are subject to change on the basis of the level of profitability that the Company actually achieves.

The following table represents the activity in our valuation allowance for the years ended December 31, 2024 and 2023:


	Year Ended December 31,
	2024		2023
Beginning balance—January 1	$	(156,870)	$	(108,504)
Valuation allowances established	(99,858)		(48,366)
Release of valuation allowances	—		—
Ending balance—December 31	$	(256,728)	$	(156,870)

The Company has utilized its remaining federal net operating loss carryforwards in 2024 and has approximately $60,683 in state net operating loss carryforwards. Certain of these loss carryforwards have an indefinite life and other amounts are available to offset future taxable income through 2043. The Company has approximately $61,198 in federal and state general business credits that are available to offset future taxable income through 2043. The Company has analyzed the impact of IRC Sections 382 and 383 on these tax attributes and has determined that no prior ownership changes have occurred which would limit the Company’s ability to utilize the NOLs and research and development tax credits.

The Company’s tax years through the 2024 tax year remain subject to examination by federal and state tax authorities.

The Company utilizes a more-likely-than-not standard in recognizing a tax benefit in its financial statements. No uncertain tax benefits have been recorded in 2024, 2023, and 2022, respectively.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147477891/740-270-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-URI https://asc.fasb.org/740/tableOfContent

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 14
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Paragraph 2
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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+ Details

STOCK-BASED COMPENSATION

12 Months Ended

Dec. 31, 2024

Equity [Abstract]

STOCK-BASED COMPENSATION

Prior to the IPO, the Company granted options to purchase shares of the Company’s common stock and restricted stock units (“RSU”) in respect of shares of the Company’s common stock to employees, directors and consultants under the Company’s 2011 Equity Incentive Plan. In July 2021, Duolingo adopted the 2021 Incentive Award Plan (“2021 Plan”) and the 2021 Employee Stock Purchase Plan (“ESPP”), each of which became effective on July 26, 2021 in connection with the IPO. An aggregate of 7,946 shares and 1,119 shares of Class A common stock were made available for future issuance under the 2021 Plan and ESPP, respectively. Pursuant to the terms of the 2021 Plan, on each January 1 through January 1, 2031, the number of shares of the Company’s Class A common stock available for issuance under the 2021 Plan automatically increases by the lesser of (i) 5% of the shares outstanding on the preceding December 31 (calculated on an as-converted basis) and (ii) such smaller number of shares of common stock as determined by the Board or the Committee (as defined in the 2021 Plan). Pursuant to the terms of the ESPP, on each January 1 through January 1, 2031, the number of shares of the Company’s Class A common stock available for issuance automatically increases by the lesser of (i) 1% of the shares outstanding on the preceding December 31 and (ii) such smaller number of shares of common stock as determined by the Board or the Committee (as defined in the ESPP). On January 1, 2025, the number of Class A shares available under the 2021 Plan was increased by 2,247 shares of common stock. The Board waived the 2025 automatic annual increase of shares available for future issuance under the ESPP, and the Company intends to waive such automatic annual increase for all applicable future periods.

The Company’s stock options vest based on terms in the stock option agreements, which generally provide for vesting over four years based on continued service to the Company and its subsidiaries. Each option has a term of ten years. Stock options granted under the 2021 Plan must generally have an exercise price of not less than the estimated fair market value of the underlying Class A common stock at the date of the grant. No options have been granted under the 2021 Plan.

A summary of stock option activity under the Plans was as follows:


(In thousands, except prices and years)	Number of options	Weighted- average exercise price		Weighted- average remaining contractual life (years)	Aggregate intrinsic value





Options outstanding at January 1, 2024	2,985	$	16.04	5.60	$	629,865
Granted (1)	—
Exercised	(1,462)	13.24

Forfeited and expired (2)	—	20.75
Options outstanding at December 31, 2024	1,523	$	18.73	4.67	$	465,985
Options exercisable at December 31, 2024	1,523	$	18.65	4.67	$	465,654

________________

(1) There were no stock options granted during the year ended December 31, 2024.

(2) There was a nominal amount of forfeitures and expirations during the year ended December 31, 2024.

The total intrinsic value of options exercised was approximately $365,484, $192,456 and $140,884 for the periods ended December 31, 2024, 2023 and 2022 respectively.

A summary of RSU activity under the Plans was as follows:


(In thousands, except prices)	Restricted stock units	Weighted- average grant date fair value per share




Outstanding at January 1, 2024	2,027	$	106.32
Granted	719	199.82
Released	(821)	103.81
Forfeited	(123)	118.58
Outstanding at December 31, 2024	1,802	$	143.96

As of December 31, 2024, there was approximately $23 of unrecognized stock-based compensation expense related to stock options granted under the plans with a weighted-average period of approximately 2 months. The amount of unrecognized stock-based compensation expense for RSUs as of December 31, 2024 was $239,138 with a weighted-average period of approximately three years. Total unrecognized compensation expense as of December 31, 2024 was $239,161.

There were 8,951 shares available for grant at December 31, 2024.

Performance-based RSUs

In June 2021, the Company granted an aggregate of 1,800 performance-based RSUs (the “Founder Awards”) to the Company’s founders. The Founder Awards vest upon the satisfaction of both a service-based condition and a performance-based condition and generally are settled one year after vesting. The service-based condition is satisfied as to 25% of the Founder Awards on each anniversary of the IPO on July 27, 2021, subject to the continuous service of the founders through the applicable date. The performance-based condition will be satisfied with respect to each of 10 equal tranches only if the trailing 60-calendar day volume-weighted-average closing trading price of the Company’s Class A common stock reaches certain stock-price hurdles for each such tranche, as set forth below, over a period of 10 years from the date of grant.

Any RSUs associated with stock-price hurdles not achieved by the tenth anniversary of the date of grant will terminate and be canceled for no additional consideration to the founders. The stock-price hurdles and number of RSUs eligible to vest will be adjusted to reflect any stock splits, stock dividends, combinations, reorganizations, reclassifications, or similar events under the 2021 Plan. The Founder Awards will be settled in shares of the Company’s Class B common stock.


Tranche	Company Stock Price Hurdle		Number of RSUs Eligible to Vest
1 (1)	$	127.50	90
2 (1)	$	153.00	90
3 (2)	$	178.50	90
4 (3)	$	204.00	180
5 (4)	$	255.00	180
6 (5)	$	306.00	180
7	$	357.00	180
8	$	408.00	180
9	$	612.00	270
10	$	816.00	360

________________

(1) Stock price hurdle for the tranche was achieved in 2021, the service condition satisfied in 2022, and shares were released to CEO and CTO on August 14, 2023. Of the 180 shares underlying RSUs released, an aggregate of 96 shares were disbursed to the founders in a net-share settlement, and 84 shares were withheld by the Company to cover the founders’ tax withholding obligations.

(2) Stock price hurdle and the service condition for the tranche was achieved as of November 22, 2023; the shares were released after the one-year holding requirement was satisfied on November 22, 2024. Of the 90 shares underlying RSUs released, an aggregate of 42 shares were disbursed to the founders in a net-share settlement, and 48 shares were withheld by the Company to cover the founders’ tax withholding obligations.

(3) Stock price hurdle and the service condition for the tranche was achieved as of December 26, 2023; the shares were released after the one-year holding requirement was satisfied on December 26, 2024. Of the 180 shares underlying RSUs released, an aggregate of 85 shares were disbursed to the founders in a net-share settlement, and 95 shares were withheld by the Company to cover the founders’ tax withholding obligations.

(4) Stock price hurdle and the service condition for the tranche was achieved as of October 18, 2024; the shares will be released after the one-year holding requirement has been satisfied.

(5) Stock price hurdle and the service condition for the tranche was achieved as of November 26, 2024; the shares will be released after the one-year holding requirement has been satisfied.

The Company estimated the grant date fair value of the Founder Awards using a model based on multiple stock-price paths developed through the use of a Monte Carlo simulation that incorporates into the valuation the possibility that the stock-price hurdles may not be satisfied. The weighted-average grant date fair value of the Founder Awards was estimated to be $61.56 per share using the below inputs.


Input			Assumption
Valuation Date			June 28, 2021
Risk-free interest rate			1.48%
Expected life			9.98
Expected volatility			51.67%
Dividend yield			0.00%
Fair value of common stock			$95.00

The Company estimates that it will recognize total stock-based compensation expense of approximately $110,817 over the derived service period of each of the ten separate tranches which is between 3.58 – 5.92 years. If the stock-price hurdles are met sooner than the requisite service period, the stock-based compensation expense will be adjusted to prospectively recognize the remaining expense over the remaining derived service period. Provided that the founders continue to provide services to the Company, stock-based compensation expense is recognized over the derived service period, regardless of whether the stock-price hurdles are achieved.

The Company recognized $19,799, $26,622 and $30,997 of stock-based compensation expense related to the Founders Awards for the years ended December 31, 2024, 2023 and 2022, respectively, which is included within General and administrative in the Consolidated Statements of Operations and Comprehensive Income (Loss). As of December 31, 2024, there is $16,936 of unrecognized stock-based compensation expense related to these awards.

Total stock-based compensation expense was $110,477, $95,221 and $73,820 for the years ended December 31, 2024, 2023 and 2022, respectively.

Stock-based compensation expense is included in the Consolidated Statements of Operations and Comprehensive Income (Loss) as shown in the following table:


	Year Ended December 31,
(In thousands)		2024		2023		2022
Cost of revenues		$	68	$	55	$	38
Research and development		60,076		45,119		26,373
Sales and marketing		4,912		3,908		2,540
General and administrative		45,421		46,139		44,869
Total		$	110,477	$	95,221	$	73,820

Nominal amounts of stock-based compensation expense is capitalized into intangible assets for the years ended December 31, 2024 and 2023.

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	Jan. 08, 2024	Dec. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Period of letter of credit (in months)	6 months
Initial base rent per month	$ 442
Letters of credit	$ 2,656
Percentage of letter of credit (in percent)		103.00%
Restricted cash		$ 2,735	$ 2,735

STOCK-BASED COMPENSATION - Schedule of Payment Award (Details) - $ / shares shares in Thousands	Dec. 26, 2024	Nov. 22, 2024	Aug. 14, 2023	Jun. 30, 2021
1 (1) \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 127.50
Number of RSUs eligible to vest (in shares)				90
2 (1) \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 153.00
Number of RSUs eligible to vest (in shares)				90
3 (2) \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 178.50
Number of RSUs eligible to vest (in shares)				90
4 (3) \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 204.00
Number of RSUs eligible to vest (in shares)				180
5 (4) \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 255.00
Number of RSUs eligible to vest (in shares)				180
6 (5) \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 306.00
Number of RSUs eligible to vest (in shares)				180
7 \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 357.00
Number of RSUs eligible to vest (in shares)				180
8 \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 408.00
Number of RSUs eligible to vest (in shares)				180
9 \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 612.00
Number of RSUs eligible to vest (in shares)				270
10 \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company stock price hurdle (in usd per share)				$ 816.00
Number of RSUs eligible to vest (in shares)				360
Tranche One And Tranche Two \| Founder awards where performance has been met \| Founders
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Release of performance stock units (in shares)	180	90	180
Shares disbursed to founders in net-share settlement (in shares)	85	42	96
Shares withheld for taxes (in shares)	95	48	84

STOCK-BASED COMPENSATION - Schedule of Income Statement Location for Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 110,477	$ 95,221	$ 73,820
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	68	55	38
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	60,076	45,119	26,373
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	4,912	3,908	2,540
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 45,421	$ 46,139	$ 44,869

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

EARNINGS (LOSS) PER SHARE

12 Months Ended

Dec. 31, 2024

Earnings Per Share [Abstract]

EARNINGS (LOSS) PER SHARE

Basic and diluted net income (loss) per share attributable to common stockholders is presented in conformity with the two-class method required for participating securities.

Basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding during the period, less shares subject to repurchase. The diluted net income per share attributable to common stockholders is calculated by giving effect to all potential dilutive common stock equivalents outstanding for the period. The rights, including the liquidation and dividend rights, of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to 20 votes per share. Each share of Class B common stock is convertible into a share of Class A common stock voluntarily at any time by the holder, and automatically upon certain events. The Class A common stock has no conversion rights. As the liquidation and dividend rights are identical for Class A and Class B common stock, the undistributed earnings are allocated on a proportional basis and the resulting net income per share attributable to common stockholders will, therefore, be the same for both Class A and Class B common stock on an individual or combined basis.


	Year Ended December 31,
(In thousands, except per share data)		2024		2023		2022
Numerator:
Net income (loss) attributable to Class A and Class B common stockholders		$	88,574	$	16,067	(59,574)


Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, basic and diluted		43,504		41,451		39,470
Effect of dilutive securities
Founder awards where performance has been met		360		270		—
Dilutive effect of stock options outstanding (1)		1,435		2,774		—
RSUs outstanding		1,802		2,027		—
Denominator for dilutive net income per common share - weighted-average shares		47,101		46,522		39,470
Basic income (loss) per common share		$	2.04	$	0.39	$	(1.51)
Diluted income (loss) per common share		$	1.88	$	0.35	$	(1.51)

________________

(1) The Company had 1.5 million options outstanding as of December 31, 2024. The estimated dilutive effect is calculated as the number of shares expected to be issued upon vesting or exercise, adjusted for the strike price proceeds that are received by the Company and assumed to be used to repurchase shares of Duolingo common stock.

Since the Company was in a net loss position for the year ended December 31, 2022 there is no difference between the number of shares used to calculate basic and diluted loss per share. The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive are as follows:


									Year Ended December 31,
(In thousands)									2022

Stock options outstanding									180
RSUs outstanding									4,410
Founder awards where performance has been met									2,036
Total									6,626

Founder awards of 1,620, where the performance criteria has not been satisfied, are excluded from the above table because the stock-price hurdles for those awards had not been met as of December 31, 2022.

PROPERTY and EQUIPMENT, net

12 Months Ended

Dec. 31, 2024

Property, Plant and Equipment [Abstract]

PROPERTY and EQUIPMENT, net

Property and equipment consists of the following as of December 31, 2024 and December 31, 2023:



(In thousands)	December 31, 2024		December 31, 2023
Leasehold improvements	$	26,938	$	18,191
Furniture, fixtures and equipment	8,415		5,869
Total property and equipment	35,353		24,060
Less: accumulated depreciation	(16,410)		(12,268)
Total property and equipment, net	$	18,943	$	11,792

Depreciation expense is included within the following financial statement line items within the Company’s Consolidated Statements of Operations and Comprehensive Income (Loss).


	Year Ended December 31,
(In thousands)		2024		2023		2022

Research and development		$	2,358	$	1,650	$	1,500
Sales and marketing		281		190		190
General and administrative		2,326		2,260		1,428
Total		$	4,965	$	4,100	$	3,118

PROPERTY and EQUIPMENT, net - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total	$ 4,965	$ 4,100	$ 3,118
Research and development
Property, Plant and Equipment [Line Items]
Total	2,358	1,650	1,500
Sales and marketing
Property, Plant and Equipment [Line Items]
Total	281	190	190
General and administrative
Property, Plant and Equipment [Line Items]
Total	$ 2,326	$ 2,260	$ 1,428

INTANGIBLE ASSETS AND GOODWILL - Schedule of Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Amortization of capitalized computer software	$ 5,889	$ 2,995	$ 1,752
Cost of revenues
Finite-Lived Intangible Assets [Line Items]
Amortization of capitalized computer software	5,310	2,020	870
Sales and marketing
Finite-Lived Intangible Assets [Line Items]
Amortization of capitalized computer software	$ 579	$ 975	$ 882

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

REVENUE

12 Months Ended

Dec. 31, 2024

Revenue from Contract with Customer [Abstract]

REVENUE

The Company has four predominant sources of revenues; time-based subscriptions, in-app advertising placement by third parties, the Duolingo English Test, and In-App Purchases. Revenue is recognized upon transfer of control of promised products or services to users in an amount that reflects the consideration the Company expects to receive in exchange for those services. The Company does not enter into contracts with a customer that contain multiple promises that result in multiple performance

obligations. Revenue is recorded net of taxes assessed by a government authority that are both imposed on and concurrent with specific revenue transactions between Duolingo and its users.

Revenue from time-based subscriptions includes a stand-ready obligation to provide hosting services that are consumed by the customer over the subscription period. Users can purchase Duolingo monthly or they can purchase a year-long subscription and pay for the subscription at the time of purchase. Under the year-long subscription, users can also purchase a single plan or a family plan. The family plan includes up to six users on one subscription. Such payments are initially recorded to deferred revenue. The user has the ability to download limited content offline. However, as there is a significant level of integration and interdependency with the online functionality, the Company considers the service to be a single performance obligation for the online and offline content.

The Company enters into arrangements with advertising networks to monetize the in-app advertising inventory. Revenue from in-app advertising placement is recognized at a point in time when the advertisement is placed and is based upon the amount received.

Duolingo English Test revenue is generally recognized once the tests have gone through the proctoring process and a certification decision has been made. This process usually takes less than 48 hours after the test has been completed and uploaded. Customers have 21 days from the date of purchase to take the exam or their purchase will expire and revenue will be recognized. Virtually all customers complete their exams prior to expiration. Sometimes organizations may purchase tests in bulk via coupons with a one year expiration date. The Company will defer revenue from all tests that have neither been proctored nor expired.

The Company’s users have the option to purchase consumable in-app virtual goods. The Company recognizes revenue over the period in which the user consumes the virtual good, which is generally within a month.

The Company also recognizes revenue from Dos Lenguas LLC “Duo’s Taquería”, a restaurant that opened during 2022, in the space adjacent to Duolingo’s headquarters in Pittsburgh. Revenue from Duo’s Taquería is recognized at a point in time when the sales are made.

Principal Agent Considerations—The Company makes its application available to be downloaded through third-party digital distribution service providers. Users who purchase subscriptions also pay through the respective app stores. The Company evaluates the purchases via third-party payment processors to determine whether its revenues should be reported gross or net of fees retained by the payment processor. The Company is the principal in the transaction with the end user as a result of controlling, hosting, and integrating the delivery of the virtual items to the end user. The Company records revenue gross as a principal and records fees paid to third-party payment processors as Cost of revenues.

Contract Balances—Deferred revenue mostly consists of payments received in advance of revenue recognition, and is mostly related to time-based subscriptions, which will be recognized into revenue over the course of the upcoming year (recognized over 12 months or less). Additionally, the Duolingo English Test has deferred revenue related to tests that have been purchased, but will not be recognized until the tests have been proctored.

Disaggregation of Revenue

In accordance with ASC 606, Revenue from Contracts with Customers, the Company disaggregates revenue from contracts with customers into revenue streams, which most closely depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors.


	Year Ended December 31,
(In thousands)		2024		2023		2022
Revenues:
Subscription		$	607,531	$	404,684	$	273,507
Other (1)		140,493		126,425		95,988
Total revenues		$	748,024	$	531,109	$	369,495

________________

(1) Other revenue is comprised of the below.


	Year Ended December 31,
(In thousands)		2024		2023		2022
Advertising		$	54,907	$	49,858	$	44,731
Duolingo English Test		45,640		41,212		32,718
In-App Purchases		38,653		34,673		17,914
Other		1,293		682		625
Total other revenue		$	140,493	$	126,425	$	95,988

Three service providers, Apple, Google and Stripe, processed 60.8%, 23.4%, and 11.7% of total revenues for the year ended December 31, 2024, respectively. Three services providers, Apple, Google, and Stripe processed 58.5%, 25.6% and 12.1% of total revenues for the year ended December 31, 2023, respectively. Two services providers, Apple and Google, processed 54.2% and 28.1% of total revenues for the year ended December 31, 2022, respectively.

Information regarding geography of revenues is based upon the location where the users are located or, in the case of the Duolingo English Test, where the tests are taken:


	Year Ended December 31,
	2024		2023		2022
United States	$	311,539	$	238,759	$	168,320

Rest of World	436,485		292,350		201,175
Total	$	748,024	$	531,109	$	369,495

Customers located in the United States accounted for 42%, 45% and 46% of total revenues for the years ended December 31, 2024, 2023 and 2022, respectively. No other country accounted for more than 10% of revenue in the periods presented.

Changes in deferred revenues were as follows:


	Year Ended December 31,
(In thousands)	2024		2023
Beginning balance—January 1	$	249,192	$	157,550
Amount from beginning balance recognized into revenue	(248,667)		(157,550)
Recognition of deferred revenue	(402,937)		(287,429)
Deferral of revenue	775,296		536,621
Ending balance—December 31	$	372,884	$	249,192

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-10

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-15

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org/606/tableOfContent

+ Details

INCOME TAXES - Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Deferred Tax Assets, Valuation Allowance [Roll Forward]
Beginning balance	$ (156,870)	$ (108,504)
Valuation allowances established	(99,858)	(48,366)
Release of valuation allowances	0	0
Ending balance	$ (256,728)	$ (156,870)

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2024
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

STOCK-BASED COMPENSATION - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Number of options
Options outstanding, beginning balance (in shares)	2,985,000
Granted (in shares)	0
Exercised (in shares)	(1,462,000)
Forfeited and expired (in shares)	0
Options outstanding, ending balance (in shares)	1,523,000	2,985,000
Number of options exercisable (in shares)	1,523,000
Weighted- average exercise price
Outstanding, beginning balance (in usd per share)	$ 16.04
Granted (in usd per share)
Exercised (in usd per share)	13.24
Forfeited and expired (in usd per share)	20.75
Outstanding, ending balance (in usd per share)	18.73	$ 16.04
Weighted average exercise price, options exercisable (in usd per share)	$ 18.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term (in years), outstanding	4 years 8 months 1 day	5 years 7 months 6 days
Weighted average remaining contractual term (in years), exercisable	4 years 8 months 1 day
Aggregate intrinsic value, outstanding	$ 465,985	$ 629,865
Aggregate intrinsic value, exercisable	$ 465,654

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

Principles of Consolidation

Principles of Consolidation—The Consolidated Financial Statements include the accounts of the Company and subsidiaries over which the Company has control. All intercompany transactions and balances have been eliminated.

Basis of Presentation and Accounting Principles

Basis of Presentation—The accompanying Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the U.S. (“GAAP”) from the Company’s accounting records and reflect the consolidated financial position and results of operations for the years ended December 31, 2024, 2023, and 2022. Unless otherwise specified, all dollar amounts (other than per share amounts) are referred to in thousands.

Accounting Principles—The Consolidated Financial Statements and accompanying notes are prepared in accordance with GAAP.

Use of Estimates

Revenue Recognition

obligations. Revenue is recorded net of taxes assessed by a government authority that are both imposed on and concurrent with specific revenue transactions between Duolingo and its users.

Disaggregation of Revenue

Cash and Cash Equivalents

Investments

Restricted Cash

Accounts Receivable

Property and Equipment

Property and Equipment—Property and equipment is stated at cost, less accumulated depreciation. Depreciation is computed on the straight-line method.


Asset Class			Estimated Useful Life
Furniture, fixtures and equipment			4 to 6 years
Leasehold improvements			5 to 10 years

The second step is to measure the tax benefit as the largest amount that is 50% likely of being realized upon settlement with a tax authority.

Foreign Currency

Fair Value of Financial Instruments

Research and Development Costs

Sales and Marketing

General and Administrative

insurance, facilities costs, and other general overhead costs that support our operations, and depreciation of certain property and equipment.

Concentration of Credit Risk

Stock-Based Compensation

Restricted Stock Units (RSUs)

Performance-based RSUs

Contingencies

Segment

Leases

Impairment of long-lived assets

Allowance for Credit Losses

Recently Issued Pronouncements Not Yet Adopted and Recently Adopted Accounting Pronouncements

Recently Issued Pronouncements Not Yet Adopted

Recently Adopted Accounting Pronouncements

Fair Value

The Company accounts for certain assets and liabilities at fair value in accordance with the accounting guidance applicable to fair value measurements and disclosures. The carrying values of cash, cash equivalents, accounts receivable, accounts payable, and accrued expenses are deemed to be reasonable estimates of their fair values because of their short-term nature.

The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring and non-recurring basis. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities, which are required to be recorded at fair value, the Company considers the principal or most advantageous market in which the Company would transact and the market-based risk measurements or assumptions that market participants would use in pricing the asset or liability, such as inherent risk, transfer restrictions, and credit risk.

The Company applies the following fair value hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1—Observable inputs such as quoted prices in active markets for identical investments that the Company has the ability to access.

Level 2—Inputs include:

•Quoted prices for similar assets or liabilities in active markets;

•Quoted prices for identical or similar assets or liabilities in inactive markets;

•Inputs, other than quoted prices in active markets, which are observable either directly or indirectly;

•Inputs that are derived principally from, or corroborated by, observable market data by correlation or other means.

Level 3—Unobservable inputs in which there is little or no market activity for the asset or liability, which require the reporting entity to develop its own estimates and assumptions relating to the pricing of the asset or liability including assumptions regarding risk.

FAIR VALUE - Narrative (Details) - USD ($)	12 Months Ended
FAIR VALUE - Narrative (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Accrued interest	$ 1,487,000	$ 0
Other-than-temporary impairments	$ 0	$ 0
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets
Minimum
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term investments, maturity term (in years)	1 year	1 year
Maximum
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term investments, maturity term (in years)	7 years	7 years

FAIR VALUE - Schedule of Net Unrealized Gains (Losses), and Fair Value by Major Security Type for Our Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash	$ 73,351	$ 50,373
Gross Unrealized Gains	21	0
Gross Unrealized Losses	(571)	0
Amortized Cost	901,186	697,237
Fair Value	975,386	747,610
Short-term investments	91,854	0
Cash and cash equivalents	785,791	747,610
Long-Term Investments	98,292	0
Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Securities, Held-To-Maturity, Fair Value And Cash Equivalents, At Carrying Value	728,101
Debt Securities, Held-To-Maturity, Amortized Cost, After Allowance For Credit Loss And Cash Equivalents, At Carrying Value	728,099
Gross Unrealized Gains	2
Gross Unrealized Losses	(1)
Level 1 \| Commercial paper
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	15,659
Fair Value	15,661
Level 1 \| Money market funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash Equivalents	712,440	$ 697,237
Level 1 \| Cash Equivalents
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash Equivalents	712,440
Level 1 \| Cash Equivalents \| Money market funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash Equivalents	712,440
Level 1 \| Short-Term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term investments	15,659
Level 1 \| Short-Term Investments \| Commercial paper
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term investments	15,659
Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	173,087
Gross Unrealized Gains	19
Gross Unrealized Losses	(570)
Fair Value	172,534
Short-term investments	76,195
Debt securities, held to maturity	96,892
Level 2 \| Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	16,280
Gross Unrealized Gains	10
Gross Unrealized Losses	(1)
Fair Value	16,289
Short-term investments	697
Debt securities, held to maturity	15,583
Level 2 \| Certificates of deposit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	11,521
Gross Unrealized Losses	(14)
Fair Value	11,507
Short-term investments	11,521
Level 2 \| Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	126,031
Gross Unrealized Gains	7
Gross Unrealized Losses	(494)
Fair Value	125,543
Short-term investments	55,013
Debt securities, held to maturity	71,018
Level 2 \| U.S. Treasury securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	19,255
Gross Unrealized Gains	2
Gross Unrealized Losses	(61)
Fair Value	19,195
Short-term investments	8,964
Debt securities, held to maturity	10,291
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment in SAFE	$ 1,400

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2024
Audit Information [Abstract]
Auditor Name	Deloitte & Touche LLP
Auditor Location	New York, New York
Auditor Firm ID	34

INTANGIBLE ASSETS AND GOODWILL - Schedule of Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 4,050
Acquisitions	6,488
Ending balance	$ 10,538

- Definition

+ References

+ Details

EMPLOYEE BENEFIT PLAN (Details) - USD ($)	12 Months Ended
EMPLOYEE BENEFIT PLAN (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, contributions by employer	$ 6,965,000	$ 5,908,000	$ 4,624,000
Defined contribution plan, employer discretionary contribution amount	$ 0	$ 0	$ 0
First 4% of Employee Elective Deferral
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of match (in percent)	100.00%
Employer matching contribution, percent of employees' gross pay (in percent)	4.00%
Next 2% of Employee Elective Deferral
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of match (in percent)	50.00%
Employer matching contribution, percent of employees' gross pay (in percent)	2.00%

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

Schedule of Useful Life


Asset Class			Estimated Useful Life
Furniture, fixtures and equipment			4 to 6 years
Leasehold improvements			5 to 10 years

Property and equipment consists of the following as of December 31, 2024 and December 31, 2023:



(In thousands)	December 31, 2024		December 31, 2023
Leasehold improvements	$	26,938	$	18,191
Furniture, fixtures and equipment	8,415		5,869
Total property and equipment	35,353		24,060
Less: accumulated depreciation	(16,410)		(12,268)
Total property and equipment, net	$	18,943	$	11,792

Depreciation expense is included within the following financial statement line items within the Company’s Consolidated Statements of Operations and Comprehensive Income (Loss).


	Year Ended December 31,
(In thousands)		2024		2023		2022

Research and development		$	2,358	$	1,650	$	1,500
Sales and marketing		281		190		190
General and administrative		2,326		2,260		1,428
Total		$	4,965	$	4,100	$	3,118

INTANGIBLE ASSETS AND GOODWILL

12 Months Ended

Dec. 31, 2024

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSETS AND GOODWILL

Intangible assets consist of the following as of December 31, 2024 and December 31, 2023:


(In thousands)	December 31, 2024		December 31, 2023
Capitalized software	$	35,681	$	26,895
Acquired technology	1,007		—
Other intangible assets	117		117
Total intangible assets	36,805		27,012
Less: accumulated amortization	(16,906)		(11,017)
Intangible assets, net	$	19,899	$	15,995

The Company capitalized $9,024 and $10,394 of software development costs, with the majority of the costs being employee wages, during the years ended December 31, 2024 and 2023, respectively. The Company recognized $238 and $0 of impairment of capitalized software in Research and Development within the Company’s Consolidated Statements of Operations and Comprehensive Income (Loss), during the years ended December 31, 2024 and 2023, respectively, which represents an impairment to write-off the capitalization of an internal-use software project prior to being launched to the user base. Amortization expense is included within the following financial statement line items within the Company’s Consolidated Statements of Operations and Comprehensive Income (Loss).


	Year Ended December 31,
(In thousands)		2024		2023		2022
Cost of revenues		$	5,310	$	2,020	$	870
Sales and marketing		579		975		882
Total		$	5,889	$	2,995	$	1,752

The estimated future amortization expense of capitalized software and acquired technology with definite lives as of December 31, 2024 was as follows:


(In thousands)	Amortization Expense
2025	$	8,493
2026	6,991
2027	3,750
2028	234
2029	157
Thereafter	157
Total estimated future amortization expense	$	19,782

The following table represents the changes to goodwill during the twelve months ended December 31, 2024:


	Carrying amount
Balance as of December 31, 2023	$	4,050
Acquisitions	6,488
Balance as of December 31, 2024	$	10,538

As of December 31, 2024 and December 31, 2023, $6,923 and $3,713 of goodwill is deductible for tax purposes, respectively.

FAIR VALUE

12 Months Ended

Dec. 31, 2024

Fair Value Disclosures [Abstract]

FAIR VALUE

Level 1—Observable inputs such as quoted prices in active markets for identical investments that the Company has the ability to access.

Level 2—Inputs include:

•Quoted prices for similar assets or liabilities in active markets;

•Quoted prices for identical or similar assets or liabilities in inactive markets;

•Inputs, other than quoted prices in active markets, which are observable either directly or indirectly;

•Inputs that are derived principally from, or corroborated by, observable market data by correlation or other means.

The following table presents amortized cost, gross unrealized gains and losses, and fair value by major security type and balance sheet classification as of December 31, 2024 and December 31, 2023:


As of December 31, 2024
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Cash Equivalents		Short-Term Investments		Long-Term Investments
Cash	$	—	$	—	$	—	$	73,351	$	73,351	$	—	$	—

Level 1
Commercial paper	$	15,659	$	2	$	(1)	$	15,661	$	—	$	15,659	$	—
Money market funds	712,440		—		—		712,440		712,440		—		—
Subtotal	$	728,099	$	2	$	(1)	$	728,101	$	712,440	$	15,659	$	—

Level 2
Asset-backed securities	$	16,280	$	10	$	(1)	$	16,289	$	—	$	697	$	15,583
Certificates of deposit	11,521		—		(14)		11,507		—		11,521		—
Corporate debt securities	126,031		7		(494)		125,543		—		55,013		71,018
U.S. Treasury securities	19,255		2		(61)		19,195		—		8,964		10,291
Subtotal	$	173,087	$	19	$	(570)	$	172,534	$	—	$	76,195	$	96,892

Level 3
Investment in SAFE	$	—	$	—	$	—	$	1,400	$	—	$	—	$	1,400
Subtotal	$	—	$	—	$	—	$	1,400	$	—	$	—	$	1,400
Total	$	901,186	$	21	$	(571)	$	975,386	$	785,791	$	91,854	$	98,292


As of December 31, 2023
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Cash Equivalents		Short-Term Investments		Long-Term Investments
Cash	$	—	$	—	$	—	$	50,373	$	50,373	$	—	$	—

Level 1
Money market funds	$	697,237	$	—	$	—	$	697,237	$	697,237	$	—	$	—





Total	$	697,237	$	—	$	—	$	747,610	$	747,610	$	—	$	—

As of December 31, 2024 and December 31, 2023, all of the Company’s short-term investments have contractual maturities of one year or less and all of the Company’s long-term investments have contractual maturities between one and seven years. The Company has elected to present accrued interest within Prepaid expenses and other current assets in the Consolidated Balance Sheet, which was $1,487 and $0 as of December 31, 2024 and December 31, 2023, respectively.

Changes in market interest rates, credit risk of borrowers and overall market liquidity, amongst other factors, may cause the short-term and long-term debt investments to fall below their amortized cost basis, resulting in unrealized losses. For those debt securities in an unrealized loss position as of December 31, 2024, the Company does not intend to sell, nor is it more likely than not that it will be required to sell, such securities before recovering the amortized cost basis. No other-than-temporary impairments have been recognized in the financial statements for the periods ended December 31, 2024 and December 31, 2023.

Cash equivalents consist primarily of money market accounts with maturities of three months or less at the date of acquisition and are classified within Level 1.

The Company’s investments in corporate debt securities, U.S. Treasury securities, certificates of deposit, and asset-backed securities, which collectively are investments in held-to-maturity debt securities, are classified within Level 2, as their valuation requires quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and/or model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

SUBSEQUENT EVENTS	12 Months Ended
SUBSEQUENT EVENTS	Dec. 31, 2024
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS None.

LEASES (Tables)

12 Months Ended

Dec. 31, 2024

Leases [Abstract]

Schedule of Components of Lease Cost

The following represents the components of lease cost for the year ended December 31, 2024 and 2023 along with supplemental disclosures of cash flow information, lease term and discount rate:


	Year Ended December 31,
		2024		2023		2022
Operating lease cost		$	9,982	$	7,459	$	7,076
Short term lease cost		83		48		125
Variable lease cost		468		252		63
Total lease cost		$	10,533	$	7,759	$	7,264

Cash paid for amounts included in the measurement of lease liabilities		$	5,727	$	7,512	$	5,168
Right-of-use assets obtained in exchange for new operating lease liabilities		$	33,039	$	—	$	909
Right of use assets disposed or adjusted, modifying operating leases liabilities		$	1,302	$	2,024	$	(1,586)


	December 31, 2024		December 31, 2023		December 31, 2022
Weighted-average remaining lease term	9 years		9 years		9 years
Weighted-average discount rate	7.16	%	7.38	%	6.92	%

Schedule of Future Minimum Rental Payments for Operating Leases

The following table reconciles future minimum undiscounted rental commitments for operating leases to operating lease liabilities recorded on the Consolidated Balance Sheet as of December 31, 2024:


Fiscal year
2025	$	4,185
2026	9,134
2027	9,505
2028	9,299
2029	9,492
Thereafter	38,989
Total undiscounted lease payments	$	80,604
Present value adjustment	(23,367)
Operating lease liabilities	$	57,237

INCOME TAXES - Provision of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Current Federal, State and Local, Tax Expense (Benefit) [Abstract]
Federal	$ 10,652	$ 895	$ 302
State	2,639	607	327
Foreign	284	341	524
Current Income Tax Expense (Benefit), Total	13,575	1,843	1,153
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Federal	0	0	0
State	0	0	0
Foreign	157	(133)	(215)
Total	157	(133)	(215)
Provision for income taxes	$ 13,732	$ 1,710	$ 938

INTANGIBLE ASSETS AND GOODWILL - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	$ 36,805	$ 27,012
Less: accumulated amortization	(16,906)	(11,017)
Intangible assets, net	19,899	15,995
Capitalized software
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	35,681	26,895
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	1,007	0
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	$ 117	$ 117

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

PROPERTY and EQUIPMENT, net (Tables)

12 Months Ended

Dec. 31, 2024

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment


Asset Class			Estimated Useful Life
Furniture, fixtures and equipment			4 to 6 years
Leasehold improvements			5 to 10 years

Property and equipment consists of the following as of December 31, 2024 and December 31, 2023:



(In thousands)	December 31, 2024		December 31, 2023
Leasehold improvements	$	26,938	$	18,191
Furniture, fixtures and equipment	8,415		5,869
Total property and equipment	35,353		24,060
Less: accumulated depreciation	(16,410)		(12,268)
Total property and equipment, net	$	18,943	$	11,792

Depreciation expense is included within the following financial statement line items within the Company’s Consolidated Statements of Operations and Comprehensive Income (Loss).


	Year Ended December 31,
(In thousands)		2024		2023		2022

Research and development		$	2,358	$	1,650	$	1,500
Sales and marketing		281		190		190
General and administrative		2,326		2,260		1,428
Total		$	4,965	$	4,100	$	3,118

DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION	12 Months Ended
DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION	DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION Duolingo, Inc. (the “Company” or “Duolingo”) was formed on August 18, 2011, and the Duolingo App was launched to the general public on June 19, 2012. The Company’s headquarters are located in Pittsburgh, Pennsylvania. Duolingo is a US-based mobile learning platform, as well as a digital English language proficiency assessment exam. The Company has a freemium business model: the app and the website are accessible free of charge, although Duolingo also offers premium services for a subscription fee. As of the date of this filing, Duolingo offers courses in over 40 different languages, including Spanish, English, French, German, Italian, Portuguese, Japanese and Chinese. We have locations in the U.S., China and Germany. Principles of Consolidation—The Consolidated Financial Statements include the accounts of the Company and subsidiaries over which the Company has control. All intercompany transactions and balances have been eliminated. Basis of Presentation—The accompanying Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the U.S. (“GAAP”) from the Company’s accounting records and reflect the consolidated financial position and results of operations for the years ended December 31, 2024, 2023, and 2022. Unless otherwise specified, all dollar amounts (other than per share amounts) are referred to in thousands. The Consolidated Financial Statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”).

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2024	Dec. 31, 2023
Common Class A
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,000,000	2,000,000
Common stock, shares issued (in shares)	38,730	36,311
Common stock, shares outstanding (in shares)	38,730	36,311
Common Class B
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	30,000	30,000
Common stock, shares issued (in shares)	6,206	6,215
Common stock, shares outstanding (in shares)	6,206	6,215

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Useful Life (Details)	Dec. 31, 2024
Furniture, fixtures and equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	4 years
Furniture, fixtures and equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	6 years
Leasehold improvements \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	5 years
Leasehold improvements \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	10 years

DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION (Details)	Dec. 31, 2024 language
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of languages, more than	40

REVENUE - Schedule of Deferred Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Revenue from Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 249,192	$ 157,550
Amount from beginning balance recognized into revenue	(248,667)	(157,550)
Recognition of deferred revenue	(402,937)	(287,429)
Deferral of revenue	775,296	536,621
Ending balance	$ 372,884	$ 249,192

STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2024

Equity [Abstract]

Schedule of Share-based Payment Arrangement, Option, Activity

A summary of stock option activity under the Plans was as follows:


(In thousands, except prices and years)	Number of options	Weighted- average exercise price		Weighted- average remaining contractual life (years)	Aggregate intrinsic value





Options outstanding at January 1, 2024	2,985	$	16.04	5.60	$	629,865
Granted (1)	—
Exercised	(1,462)	13.24

Forfeited and expired (2)	—	20.75
Options outstanding at December 31, 2024	1,523	$	18.73	4.67	$	465,985
Options exercisable at December 31, 2024	1,523	$	18.65	4.67	$	465,654

________________

(1) There were no stock options granted during the year ended December 31, 2024.

(2) There was a nominal amount of forfeitures and expirations during the year ended December 31, 2024.

Schedule of Share-based Payment Arrangement, RSU, Activity

A summary of RSU activity under the Plans was as follows:


(In thousands, except prices)	Restricted stock units	Weighted- average grant date fair value per share




Outstanding at January 1, 2024	2,027	$	106.32
Granted	719	199.82
Released	(821)	103.81
Forfeited	(123)	118.58
Outstanding at December 31, 2024	1,802	$	143.96

Schedule of Share-based Payment Arrangement, Payment Award


Tranche	Company Stock Price Hurdle		Number of RSUs Eligible to Vest
1 (1)	$	127.50	90
2 (1)	$	153.00	90
3 (2)	$	178.50	90
4 (3)	$	204.00	180
5 (4)	$	255.00	180
6 (5)	$	306.00	180
7	$	357.00	180
8	$	408.00	180
9	$	612.00	270
10	$	816.00	360

________________

(4) Stock price hurdle and the service condition for the tranche was achieved as of October 18, 2024; the shares will be released after the one-year holding requirement has been satisfied.

(5) Stock price hurdle and the service condition for the tranche was achieved as of November 26, 2024; the shares will be released after the one-year holding requirement has been satisfied.

The weighted-average grant date fair value of the Founder Awards was estimated to be $61.56 per share using the below inputs.


Input			Assumption
Valuation Date			June 28, 2021
Risk-free interest rate			1.48%
Expected life			9.98
Expected volatility			51.67%
Dividend yield			0.00%
Fair value of common stock			$95.00

Schedule of Share-based Payment Arrangement, Expensed, Amount

Stock-based compensation expense is included in the Consolidated Statements of Operations and Comprehensive Income (Loss) as shown in the following table:


	Year Ended December 31,
(In thousands)		2024		2023		2022
Cost of revenues		$	68	$	55	$	38
Research and development		60,076		45,119		26,373
Sales and marketing		4,912		3,908		2,540
General and administrative		45,421		46,139		44,869
Total		$	110,477	$	95,221	$	73,820

EARNINGS (LOSS) PER SHARE - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net income (loss) attributable to Class A and Class B common stockholders	$ 88,574	$ 16,067	$ (59,574)
Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, diluted (in shares)	47,101	46,522	39,470
Effect of dilutive securities
Basic income (loss) per common share (in usd per share)	$ 2.04	$ 0.39	$ (1.51)
Diluted income (loss) per common share (in usd per share)	$ 1.88	$ 0.35	$ (1.51)
Options outstanding (in shares)	1,523	2,985
Founder awards where performance has been met
Effect of dilutive securities
Stock options and RSUs outstanding (in shares)	360	270	0
Stock options outstanding
Effect of dilutive securities
Stock options and RSUs outstanding (in shares)	1,435	2,774	0
RSUs outstanding
Effect of dilutive securities
Stock options and RSUs outstanding (in shares)	1,802	2,027	0
Class A and Class B Common Stock
Numerator:
Net income (loss) attributable to Class A and Class B common stockholders	$ 88,574	$ 16,067	$ (59,574)
Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, basic (in shares)	43,504	41,451	39,470
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, diluted (in shares)	43,504	41,451	39,470

EARNINGS (LOSS) PER SHARE (Tables)

12 Months Ended

Dec. 31, 2024

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

As the liquidation and dividend rights are identical for Class A and Class B common stock, the undistributed earnings are allocated on a proportional basis and the resulting net income per share attributable to common stockholders will, therefore, be the same for both Class A and Class B common stock on an individual or combined basis.


	Year Ended December 31,
(In thousands, except per share data)		2024		2023		2022
Numerator:
Net income (loss) attributable to Class A and Class B common stockholders		$	88,574	$	16,067	(59,574)


Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, basic and diluted		43,504		41,451		39,470
Effect of dilutive securities
Founder awards where performance has been met		360		270		—
Dilutive effect of stock options outstanding (1)		1,435		2,774		—
RSUs outstanding		1,802		2,027		—
Denominator for dilutive net income per common share - weighted-average shares		47,101		46,522		39,470
Basic income (loss) per common share		$	2.04	$	0.39	$	(1.51)
Diluted income (loss) per common share		$	1.88	$	0.35	$	(1.51)

________________

Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share

The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive are as follows:


									Year Ended December 31,
(In thousands)									2022

Stock options outstanding									180
RSUs outstanding									4,410
Founder awards where performance has been met									2,036
Total									6,626

INTANGIBLE ASSETS AND GOODWILL - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Capitalized software development costs	$ 9,024,000	$ 10,394,000
Impairment of capitalized software	238,000	0	$ 0
Goodwill, tax deductible amount	$ 6,923,000	$ 3,713,000