0001628280-26-069692 | 10-Q | XBRL Viewer

STOCKHOLDERS’ EQUITY

9 Months Ended

Sep. 30, 2026

A summary of stock option activity as of September 30, 2026 is 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, 2026	859	$	18.38	3.77	$	135,938
Granted (1)	—	—
Exercised	(377)	15.82

Forfeited and expired (2)	—	—
Options outstanding at September 30, 2026	482	$	20.36	3.44	$	59,481
Options exercisable at September 30, 2026	482	$	20.36	3.44	$	59,481

________________

(1) There were no stock options granted during the three and nine months ended September 30, 2026.

(2) There was a nominal amount of forfeitures and expirations during the three and nine months ended September 30, 2026.

The total intrinsic value of options exercised was approximately $40.7 million and $189.4 million for the nine months ended September 30, 2026 and 2025, respectively.

A summary of RSU activity as of September 30, 2026 is as follows:


(In thousands, except prices)	Restricted stock units	Weighted- average grant-date fair value per share
Outstanding at January 1, 2026	1,406	$	242.94
Granted	2,147	113.27
Released	(656)	177.86
Forfeited	(259)	206.98
Outstanding at September 30, 2026	2,638	$	157.07

As of September 30, 2026, there was no unrecognized stock-based compensation expense related to stock options granted under the plans. The amount of unrecognized stock-based compensation expense for RSUs as of September 30, 2026 was $375.8 million with a weighted-average period of approximately three years.

There were 9,209 thousand shares available for issuance under the Company’s 2021 Incentive Award Plan and 1,604 thousand shares available for issuance under the Company’s 2021 Employee Stock Purchase Plan, in each case, at September 30, 2026.

Performance-based RSUs

In June 2021, the Company granted performance-based RSUs to its founders (“Founder Awards”) that vest based on continued service and the achievement of specified stock price targets. As of September 30, 2026, certain performance conditions have been achieved, while others remain subject to future stock price performance. Stock-based compensation expense is recognized over the derived service period using an accelerated attribution method, subject to continued service.

In 2026, the Company modified the service condition applicable to the final two tranches of the Founder Awards held by one of its founders. The modification was accounted for as a Type III modification under

ASC 718. As a result of the revised service condition, the Company reversed $8.2 million of stock-based compensation expense previously recognized under the original derived service periods. The modified awards have a total compensation cost of approximately $10.0 million, based on the modified fair value determined using a Monte Carlo simulation model, representing an increase of $1.7 million, over the original grant-date fair value. The total compensation cost will be recognized over the revised derived service periods, which extend through September 30, 2029.

The Company recognized a stock-based compensation expense of $1.7 million and a stock-based compensation benefit of $4.1 million related to the Founder Awards during the three and nine months ended September 30, 2026, respectively. The Company recognized stock-based compensation expense of $1.7 million and $9.8 million for the three and nine months ended September 30, 2025, respectively. As of September 30, 2026, unrecognized stock-based compensation expense related to the Founder Awards was $10.6 million.

Stock-Based Compensation

Total stock-based compensation expense was $47.5 million and $120.3 million for the three and nine months ended September 30, 2026, respectively, and $35.6 million and $101.2 million for the three and nine months ended September 30, 2025, respectively.

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


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2026		2025		2026		2025
Cost of revenues	$	36	$	28	$	90	$	72
Research and development	30,977		22,821		80,361		61,115
Sales and marketing	2,495		1,633		6,299		4,657
General and administrative	13,969		11,083		33,584		35,331
Total	$	47,477	$	35,565	$	120,334	$	101,175

Nominal amounts of stock-based compensation expense are capitalized into intangible assets for the three and nine months ended September 30, 2026 and 2025.

Common Stock Repurchases

In February 2026, Duolingo’s Board of Directors authorized a share repurchase program of up to $400 million. During the three and nine months ended September 30, 2026, the Company repurchased a total of 48 thousand and 743 thousand shares, respectively, of the Company’s Class A common stock through open market purchases at an average per share price of $132.68 and $103.21, respectively, for a total repurchase price of $6.4 million and $76.7 million, respectively. During the three and nine months ended September 30, 2026, 51 thousand and 734 thousand of these shares were retired, respectively. The cost of the remaining 9 thousand shares is recorded as treasury stock in the Unaudited Condensed Consolidated Balance Sheets as of September 30, 2026. As of September 30, 2026, $323.3 million of the total amount authorized to be repurchased remained available.

STOCKHOLDERS’ EQUITY- Narrative (Details) $ / shares in Units, shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026 USD ($) $ / shares shares	Sep. 30, 2025 USD ($)	Sep. 30, 2026 USD ($) tranche $ / shares shares	Sep. 30, 2025 USD ($)	Feb. 26, 2026 USD ($)	Dec. 31, 2025 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value, exercised			$ 40,700,000	$ 189,400,000
Stock based compensation expense (benefit)	$ 47,477,000	$ 35,565,000	$ 120,334,000	101,175,000
Share repurchase program, authorized, amount					$ 400,000,000
Common stock repurchased (in shares) \| shares	48		743
Share price (in usd per share) \| $ / shares	$ 132.68		$ 103.21
Repurchases of common stock	$ 6,426,000		$ 76,704,000
Retirement of treasury stock (in shares) \| shares	51		734
Treasury stock (in shares) \| shares	9		9			0
Remaining authorized amount	$ 323,300,000		$ 323,300,000
RSUs outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, options	0		0
Unrecognized compensation expense, excluding options	$ 375,800,000		$ 375,800,000
Unrecognized compensation cost, weighted-average period of recognition (in years)			3 years
RSUs outstanding \| 2021 Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options available for grant (in shares) \| shares	9,209		9,209
RSUs outstanding \| 2021 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options available for grant (in shares) \| shares	1,604		1,604
Founder Awards where performance has been met
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, excluding options	$ 10,600,000		$ 10,600,000
Number of tranches \| tranche			2
Number of grantees affected \| tranche			1
Stock-based compensation expense	8,200,000
Total compensation cost			$ 10,000,000.0
Share-based payment cost			1,700,000
Stock based compensation expense (benefit)	$ 1,700,000	$ 1,700,000	$ (4,100,000)	$ 9,800,000

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Current assets
Cash and cash equivalents	$ 1,239,607	$ 1,036,389
Short-term investments	134,294	104,078
Accounts receivable	142,056	162,827
Deferred cost of revenues	106,188	102,663
Income tax receivable	618	14,067
Prepaid expenses and other current assets	29,582	16,582
Total current assets	1,652,345	1,436,606
Operating lease right-of-use assets	73,359	80,380
Long-term investments	110,120	135,098
Intangible assets, net	26,216	28,309
Property and equipment, net	53,020	36,297
Goodwill	40,341	35,335
Restricted cash	2,735	2,735
Deferred tax assets, net	203,605	227,339
Other assets	4,422	10,083
Total assets	2,166,163	1,992,182
Current liabilities
Deferred revenues	513,567	496,205
Accounts payable	13,740	7,998
Income tax payable	2,265	1,257
Accrued expenses and other current liabilities	70,536	45,688
Total current liabilities	600,108	551,148
Long-term obligation under operating leases	84,216	93,779
Deferred tax liabilities, net	242	249
Total liabilities	684,566	645,176
Commitments and contingencies
Stockholders’ equity
Class A common stock, $0.0001 par value; 2,000,000 shares authorized as of September 30, 2026 and December 31, 2025; 40,717 issued and 40,708 outstanding at September 30, 2026 and 40,368 issued and outstanding at December 31, 2025, respectively Class B common stock, $0.0001 par value; 30,000 shares authorized as of September 30, 2026 and December 31, 2025; 6,399 and 6,260 issued and outstanding at September 30, 2026 and December 31, 2025, respectively	5	5
Treasury stock, at cost; 9 and 0 shares as of September 30, 2026 and December 31, 2025, respectively.	(1,249)	0
Additional paid-in capital	1,090,840	1,058,783
Retained earnings	392,001	288,218
Total stockholders’ equity	1,481,597	1,347,006
Total liabilities and stockholders' equity	$ 2,166,163	$ 1,992,182

ACQUISITIONS	9 Months Ended
ACQUISITIONS	Sep. 30, 2026
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]
ACQUISITIONS	ACQUISITIONS On August 11, 2026, the Company completed the acquisition of certain assets of Animade Group Limited. Animade was a London-based animation and motion design studio. The acquisition expands Duolingo's Design Studio by adding an established and experienced animation and motion design team. The total aggregate transaction-related payments are expected to be $5.5 million, consisting of $5.0 million of purchase consideration paid in cash upon closing and $0.5 million of additional payments to certain employees contingent upon one year of continued service. The $5.0 million purchase consideration has been preliminarily allocated to goodwill. The service-contingent payments will be recognized as compensation expense over the service period within General and administrative expense in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income. The Company incurred $0.2 million of acquisition-related due diligence costs, which are included in General and administrative expense in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income. The purchase price allocation remains preliminary and is subject to finalization.

INTANGIBLE ASSETS AND GOODWILL - Schedule of Intangible Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Intangible Asset, Finite-Lived [Line Items]
Total intangible assets	$ 60,995	$ 54,411
Less: accumulated amortization	(34,779)	(26,102)
Intangible assets, net	26,216	28,309
Other Intangible Assets
Intangible Asset, Finite-Lived [Line Items]
Other indefinite-lived intangible assets	252	252
Capitalized software
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, before Accumulated Amortization	51,433	44,849
Other Intangible Assets
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, before Accumulated Amortization	$ 9,310	$ 9,310

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2026
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation—The Unaudited Condensed 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 Unaudited Condensed 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 three and nine months ended September 30, 2026 and 2025. Accounting Principles—The Unaudited Condensed Consolidated Financial Statements and accompanying notes are prepared in accordance with GAAP.
Use of Estimates	Use of Estimates—The preparation of Unaudited Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the Unaudited Condensed Consolidated Financial Statements and accompanying notes. Significant estimates and assumptions reflected in the Unaudited Condensed 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, contingent liabilities, 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 Unaudited Condensed Consolidated Financial Statements will be affected.
Advertising Costs	Advertising Costs—Advertising costs were approximately $28.0 million and $84.4 million for the three and nine months ended September 30, 2026, and $25.5 million and $62.7 million for the three and nine months ended September 30, 2025, respectively, and are included within Sales and marketing in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income.
Income Taxes	Income Taxes—The Company’s provision for income taxes is computed by using an estimate of the annual effective tax rate, adjusted for discrete items taken into account in the relevant period, if any. Each quarter, the annual effective income tax rate is recomputed and if there are material changes in the estimate, a cumulative adjustment is made.
Concentration of Credit Risk	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 deposits and certificates of deposit with banks which exceed the Federal Deposit Insurance Corporation (“FDIC”) insured limit and money market accounts which are not FDIC insured. Management believes that the financial institutions that hold the Company’s deposits are financially creditworthy and, accordingly, minimal credit risk exists with respect to those balances.
Segment	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 of virtual goods (“IAPs”). 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 Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income. 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.
Impairment of long-lived assets	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.
Allowance for Credit Losses	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. There is no allowance for credit losses for all periods presented.
Recently Issued Pronouncements Not Yet Adopted and Recently Adopted Accounting Pronouncements	Recently Issued Pronouncements Not Yet Adopted 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 currently evaluating the disclosure requirements related to the new standard. In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software. The amendments in this update remove all references to prescriptive and sequential software development stages (referred to as “project stages”) throughout Subtopic 350-40. The amendments in this update are effective for all entities for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. The Company is in the process of evaluating the effect that the adoption of this standard may have on its consolidated financial statements. Recently Adopted Accounting Pronouncements There are no recently adopted accounting pronouncements.
Fair Value	FAIR VALUE 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 identical or 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.
Disaggregation of Revenue	Disaggregation of Revenue In accordance with Accounting Standards Codification ("ASC") 606, Revenue from Contracts with Customers, the Company disaggregates revenue from contracts with customers into revenue streams, which most closely depict how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors.

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	(Accumulated Deficit) Retained Earnings
Beginning balance (in shares) at Dec. 31, 2024		44,936
Beginning balance at Dec. 31, 2024	$ 824,550	$ 4	$ 0	$ 950,393	$ (125,847)
Beginning balance (in shares) at Dec. 31, 2024			0
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	101,175			101,175
Stock options exercised (in shares)		538
Stock options exercised	9,703	$ 1		9,702
Release of restricted stock units (in shares)		635
Net income	372,111				372,111
Ending balance (in shares) at Sep. 30, 2025		46,109
Ending balance at Sep. 30, 2025	1,307,539	$ 5	$ 0	1,061,270	246,264
Ending balance (in shares) at Sep. 30, 2025			0
Beginning balance (in shares) at Jun. 30, 2025		45,787
Beginning balance at Jun. 30, 2025	977,031	$ 4	$ 0	1,022,958	(45,931)
Beginning balance (in shares) at Jun. 30, 2025			0
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	35,565			35,565
Stock options exercised (in shares)		100
Stock options exercised	2,748	$ 1		2,747
Release of restricted stock units (in shares)		222
Net income	292,195				292,195
Ending balance (in shares) at Sep. 30, 2025		46,109
Ending balance at Sep. 30, 2025	1,307,539	$ 5	$ 0	1,061,270	246,264
Ending balance (in shares) at Sep. 30, 2025			0
Beginning balance (in shares) at Dec. 31, 2025		46,628
Beginning balance at Dec. 31, 2025	$ 1,347,006	$ 5	$ 0	1,058,783	288,218
Beginning balance (in shares) at Dec. 31, 2025	0		0
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	$ 120,334			120,334
Release of performance stock units (in shares)		360
Taxes paid related to net-share settlements of share-based compensation awards ( in shares)		(171)
Taxes paid related to net-share settlements of share-based compensation awards	$ (18,799)			(18,799)
Stock options exercised (in shares)	377	377
Stock options exercised	$ 5,977			5,977
Release of restricted stock units (in shares)		656
Repurchases of common stock (in shares)	(743)		(743)
Repurchases of common stock	$ (76,704)		$ (76,704)
Retirement of treasury stock (in shares)	(734)	(734)	734
Retirement of treasury stock	$ 0		$ 75,455	(75,455)
Net income	103,783				103,783
Ending balance (in shares) at Sep. 30, 2026		47,116
Ending balance at Sep. 30, 2026	$ 1,481,597	$ 5	$ (1,249)	1,090,840	392,001
Ending balance (in shares) at Sep. 30, 2026	(9)		(9)
Beginning balance (in shares) at Jun. 30, 2026		46,736
Beginning balance at Jun. 30, 2026	$ 1,409,742	$ 5	$ (1,425)	1,046,326	364,836
Beginning balance (in shares) at Jun. 30, 2026			(12)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	47,477			47,477
Stock options exercised (in shares)		154
Stock options exercised	$ 3,639			3,639
Release of restricted stock units (in shares)		277
Repurchases of common stock (in shares)	(48)		(48)
Repurchases of common stock	$ (6,426)		$ (6,426)
Retirement of treasury stock (in shares)	(51)	(51)	51
Retirement of treasury stock	$ 0		$ 6,602	(6,602)
Net income	27,165				27,165
Ending balance (in shares) at Sep. 30, 2026		47,116
Ending balance at Sep. 30, 2026	$ 1,481,597	$ 5	$ (1,249)	$ 1,090,840	$ 392,001
Ending balance (in shares) at Sep. 30, 2026	(9)		(9)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2026 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2026 USD ($) segment	Sep. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)
Concentration Risk [Line Items]
Advertising costs	$ 28,000,000.0	$ 25,500,000	$ 84,400,000	$ 62,700,000
Number of reportable segments \| segment			1
Number of operating segments \| segment			1
Impairment of capitalized software	1,600,000	0	$ 2,134,000	0
Allowance for credit losses	0		0		$ 0
Accounts payable	13,740,000		13,740,000		7,998,000
Board of Directors Chairman
Concentration Risk [Line Items]
Vendor expenses	200,000	$ 200,000	600,000	$ 500,000
Accounts payable	$ 0		$ 0		$ 800,000
Apple \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk (in percent)			69.90%		62.50%
Google \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk (in percent)			13.90%		22.70%
Stripe \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk (in percent)					11.40%

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025
Commitments and Contingencies Disclosure [Abstract]
Loss contingency accrual		$ 5,000
Period of letter of credit (in months)	6 months
Initial base rent per month	$ 400
Letters of credit	$ 2,700
Percentage of letter of credit (in percent)	103.00%
Restricted cash	$ 2,735		$ 2,735

COMMITMENTS AND CONTINGENCIES	9 Months Ended
COMMITMENTS AND CONTINGENCIES	Sep. 30, 2026
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. Legal costs incurred in connection with the resolution of claims and lawsuits are generally expensed as incurred and are included in General and administrative expense within our Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income. The Company establishes reserves for the outcome of litigation where losses are deemed probable and reasonably estimable. The Company’s assessment of the current exposure could change in the event of the discovery of additional facts with respect to legal matters pending against the Company or determinations by judges, juries, administrative agencies or other finders of fact that are not in accordance with the Company’s evaluation of claims. Actual liabilities may exceed the amounts reserved, and there can be no assurance that final resolution of these matters will not have a material adverse effect on the Company’s financial condition, results of operations or cash flows. During 2026, the Company accrued approximately $5.0 million for certain proposed legal settlement charges, representing the Company's expected amount of the total settlement obligation, with the remainder expected to be funded by insurance. This amount is not material to the Company's financial condition, results of operations or cash flows. 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 the Company of all terms, covenants and conditions of the lease agreement. The amount of the letter of credit is equal to six months’ rent of $0.4 million, totaling $2.7 million. The cash collateral for the letter of credit has been recognized as restricted cash in the Unaudited Condensed Consolidated Balance Sheet and is equivalent to 103% of the letter of credit and totaled $2.7 million.

REVENUE - Schedule of Changes in Deferred Revenues (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025
Revenue from Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 496,205	$ 372,884
Amount from beginning balance recognized into revenue	(453,778)	(339,992)
Deferral of revenue	844,942	754,123
Amount recognized from current-period deferrals	(373,802)	(345,288)
Ending balance	$ 513,567	$ 441,728

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025
Cash flows from operating activities:
Net income	$ 103,783,000	$ 372,111,000
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	23,727,000	(239,486,000)
Stock-based compensation expense	120,334,000	101,175,000
Depreciation and amortization	12,718,000	10,583,000
Accretion on marketable securities, net	(983,000)	(1,458,000)
Impairment of capitalized software	2,134,000	0
Changes in assets and liabilities:
Deferred revenue	17,362,000	68,844,000
Accounts receivable	20,771,000	4,434,000
Deferred cost of revenues	(3,525,000)	(14,408,000)
Prepaid expenses and other current assets	449,000	(11,734,000)
Accounts payable	5,653,000	(2,813,000)
Accrued expenses and other current liabilities	21,330,000	(5,190,000)
Noncurrent assets and liabilities	4,722,000	(1,513,000)
Net cash provided by operating activities	328,475,000	280,545,000
Cash flows from investing activities:
Purchases of investments	(122,532,000)	(99,120,000)
Maturities and paydowns of investments	118,277,000	82,077,000
Capitalized software development costs and purchases of intangible assets	(8,718,000)	(6,484,000)
Purchase of property and equipment	(18,001,000)	(7,369,000)
Acquisitions of companies, net of $0 cash acquired	(5,006,000)	(33,100,000)
Net cash used for investing activities	(35,980,000)	(63,996,000)
Cash flows from financing activities:
Proceeds from exercise of stock options	5,977,000	9,702,000
Payment of earn-out related to a previous acquisition	0	(500,000)
Repurchase of common stock	(76,455,000)	0
Taxes paid related to net-share settlement of share-based compensation awards	(18,799,000)	0
Net cash (used for) provided by financing activities	(89,277,000)	9,202,000
Net increase in cash, cash equivalents and restricted cash	203,218,000	225,751,000
Cash, cash equivalents and restricted cash - Beginning of period	1,039,124,000	788,526,000
Cash, cash equivalents and restricted cash - End of period	1,242,342,000	1,014,277,000
Supplemental disclosure of cash flow information:
Cash paid for income taxes	3,552,000	11,722,000
Cash Flow, Noncash Investing and Financing Activities Disclosure :
Property and equipment included in Current liabilities	2,763,000	2,179,000
Landlord incentive included in Other assets	0	6,809,000
Right of use assets obtained in exchange for new operating lease liabilities	2,806,000	36,025,000
Repurchases of common stock included in Current liabilities	$ 249,000	$ 0

REVENUE - Narrative (Details)	3 Months Ended		9 Months Ended
REVENUE - Narrative (Details)	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Maximum
Disaggregation of Revenue [Line Items]
Subscription period (in years)	12 months		12 months
Apple \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	59.60%	62.20%	59.80%	61.60%
Google \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	23.30%	23.30%	23.10%	23.50%
Stripe \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	12.10%		11.80%	10.10%

EMPLOYEE BENEFIT PLAN	9 Months Ended
EMPLOYEE BENEFIT PLAN	Sep. 30, 2026
Postemployment Benefits [Abstract]
EMPLOYEE BENEFIT PLAN	EMPLOYEE BENEFIT PLAN The Company sponsors a profit sharing plan with an Internal Revenue Code Section 401(k) feature, the Duolingo Retirement Trust (the “Plan”), for eligible employees. The 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 $2.4 million and $7.1 million during the three and nine months ended September 30, 2026, respectively, and $2.2 million and $6.2 million during the three and nine months ended September 30, 2025, respectively. The Company did not make any discretionary matching or profit sharing contributions during the three and nine months ended September 30, 2026 or 2025.

PROPERTY AND EQUIPMENT, NET - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Property, Plant, and Equipment [Line Items]
Total property and equipment	$ 78,590	$ 57,868
Less: accumulated depreciation	(25,570)	(21,571)
Total property and equipment, net	53,020	36,297
Leasehold improvements
Property, Plant, and Equipment [Line Items]
Total property and equipment	58,073	44,773
Furniture, fixtures and equipment
Property, Plant, and Equipment [Line Items]
Total property and equipment	$ 20,517	$ 13,095

FAIR VALUE - Schedule of Net Unrealized Gains (Losses), and Fair Value by Major Security Type for Our Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash	$ 240,707	$ 155,840
Gross Unrealized Gains	2	435
Gross Unrealized Losses	(1,426)	(19)
Amortized Cost	1,241,914	1,118,326
Fair Value	1,482,597	1,275,982
Short-term investments	134,294	104,078
Cash and cash equivalents	1,239,607	1,036,389
Long-Term Investments	110,120	135,098
Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(31)	0
Amortized Cost	1,010,489	882,874
Fair Value	1,010,458	882,874
Level 1 \| Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash Equivalents	998,900	880,549
Level 1 \| Balance Sheet Location [Axis]: us-gaap:DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLossCurrent
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term investments	11,589	2,324
Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	231,425	235,452
Gross Unrealized Gains	2	435
Gross Unrealized Losses	(1,395)	(19)
Fair Value	230,032	235,868
Short-term investments	122,705	101,754
Long-Term Investments	108,720	133,698
Level 2 \| Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	27,084	26,794
Gross Unrealized Gains	0	44
Gross Unrealized Losses	(59)	0
Fair Value	27,025	26,838
Short-term investments	0	347
Long-Term Investments	27,084	26,447
Level 2 \| Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	166,619	182,417
Gross Unrealized Gains	2	237
Gross Unrealized Losses	(901)	(19)
Fair Value	165,720	182,635
Short-term investments	105,527	93,997
Long-Term Investments	61,092	88,420
Level 2 \| U.S. Treasury securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	37,722	26,241
Gross Unrealized Gains	0	154
Gross Unrealized Losses	(435)	0
Fair Value	37,287	26,395
Short-term investments	17,178	7,410
Long-Term Investments	20,544	18,831
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment in SAFE	1,400	1,400
Commercial paper \| Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortized Cost	11,589	4,318
Fair Value	11,558	4,318
Commercial paper \| Level 1 \| Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash Equivalents	0	1,993
Commercial paper \| Level 1 \| Balance Sheet Location [Axis]: us-gaap:DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLossCurrent
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term investments	11,589	2,324
Money market funds \| Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash Equivalents	998,900	878,556
Money market funds \| Level 1 \| Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash Equivalents	$ 998,900	$ 878,556

FAIR VALUE - Narrative (Details) - USD ($)	9 Months Ended
FAIR VALUE - Narrative (Details) - USD ($)	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Accrued interest	$ 1,900,000		$ 2,100,000
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets
Other-than-temporary impairments	$ 0	$ 0
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)	5 years		5 years

DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION (Details)	Sep. 30, 2026 language
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of languages, more than	250

ACQUISITIONS (Details) - USD ($) $ in Thousands	Aug. 11, 2026	Sep. 30, 2026	Dec. 31, 2025
Business Combination [Line Items]
Goodwill		$ 40,341	$ 35,335
Animade Transaction
Business Combination [Line Items]
Total aggregate transaction-related payments	$ 5,500
Purchase consideration paid in cash upon closing	5,000
Additional payments to certain employees contingent upon one year of continued service	500
Acquisition costs	200
Goodwill	$ 5,000

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2026	Nov. 03, 2026
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2026
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	141 S St Clair Street,
Entity Address, Address Line Two	Suite 501
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, par value $0.0001 per share
Trading Symbol	DUOL
Security Exchange Name	NASDAQ
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
Entity Shell Company	false
Entity Central Index Key	0001562088
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		40,779,003
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		6,399,257

EMPLOYEE BENEFIT PLAN (Details) - USD ($)	3 Months Ended		9 Months Ended
EMPLOYEE BENEFIT PLAN (Details) - USD ($)	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, contributions by employer	$ 2,400,000	$ 2,200,000	$ 7,100,000	$ 6,200,000
Defined contribution plan, employer discretionary contribution amount	$ 0	$ 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%

DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION	9 Months Ended
DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION	Sep. 30, 2026
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 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 over 250 total language courses, including Spanish, English, French, German, Italian, Portuguese, Japanese and Chinese. We have locations in the U.S., China, Germany and the United Kingdom. Principles of Consolidation—The Unaudited Condensed 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 Unaudited Condensed 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 three and nine months ended September 30, 2026 and 2025. The Unaudited Condensed Consolidated Financial Statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such SEC rules. We believe that the disclosures made are adequate to make the information presented not misleading. In our opinion, all adjustments considered necessary for a fair presentation of the financial statements have been included, and all adjustments are of a normal and recurring nature. We applied the accounting policies consistently with those used in the preparation of the Annual Report on Form 10-K in preparing these Unaudited Condensed Consolidated Financial Statements in this Quarterly Report on Form 10-Q. These Unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited financial statements and the notes for the fiscal year ended December 31, 2025 included in the Annual Report on Form 10-K and filed with the SEC.

SUBSEQUENT EVENTS	9 Months Ended
SUBSEQUENT EVENTS	Sep. 30, 2026
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On October 7, 2026, a putative shareholder class action was filed in the United States District Court for the Western District of Pennsylvania captioned City of Dearborn Heights Act 345 Police & Fire Retirement System v. Duolingo, Inc., et al., Case No. 26-cv-02197 (W.D. Pa.) (the “Securities Class Action”). The complaint names the Company and certain of its current and former executive officers as defendants and alleges violations of Sections 10(b) and 20(a) of the Exchange Act. The complaint seeks unspecified damages, as well as attorneys’ fees and costs. Motions to be appointed lead plaintiff are due December 7, 2026. The Company intends to defend against the claims in the Securities Class Action vigorously. The results of any current or future litigation cannot be predicted with certainty, and regardless of the outcome, any litigation could have an adverse impact on the Company as a result of defense costs, settlement, judgments, the diversion of management resources, and other factors. The Company has not recorded any accrual for a contingent liability associated with these legal proceedings.

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025
Statement of Cash Flows [Abstract]
Cash acquired during acquisition	$ 0	$ 0

STOCKHOLDERS’ EQUITY - Schedule of Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2026	Dec. 31, 2025
Restricted stock units
Beginning balance (in shares)	2,638	1,406
Granted (in shares)	2,147
Released (in shares)	(656)
Forfeited (in shares)	(259)
Ending balance (in shares)	2,638
Weighted- average grant-date fair value per share
Beginning balance (in usd per share)	$ 242.94
Granted (in usd per share)	113.27
Released (in usd per share)	177.86
Forfeited (in usd per share)	206.98
Ending balance (in usd per share)	$ 157.07

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Sep. 30, 2026	Dec. 31, 2025
Statement [Line Items]
Treasury stock (in shares)	9	0
Common Class A
Statement [Line Items]
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)	40,717	40,368
Common stock, shares outstanding (in shares)	40,708	40,368
Common Class B
Statement [Line Items]
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)	6,399	6,260
Common stock, shares outstanding (in shares)	6,399	6,260

INTANGIBLE ASSETS AND GOODWILL - Schedule of Changes to Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2026 USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2025	$ 35,335
Acquisitions	5,006
Balance as of September 30, 2026	$ 40,341

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2026 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 September 4, 2026, 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) under the Exchange Act, providing for (i) the sale of the net number of shares of Class A common stock underlying 19,283 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 16,866 shares of Class A common stock. The Glance 10b5-1 Sales Plan will remain in effect until the earlier of (1) December 31, 2027, (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	September 4, 2026
Expiration Date	December 31, 2027
Arrangement Duration	483 days
Natalie Glance, Trading Arrangement, Unvested Restricted Stock Units [Member] \| Natalie Glance [Member]
Trading Arrangements, by Individual
Aggregate Available	19,283
Natalie Glance, Trading Arrangement, Class A Common Stock [Member] \| Natalie Glance [Member]
Trading Arrangements, by Individual
Aggregate Available	16,866