0001562088-23-000221 | 10-Q | XBRL Viewer

PROPERTY and EQUIPMENT, net

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Property and equipment consists of the following as of September 30, 2023 and December 31, 2022:



(In thousands)	September 30, 2023		December 31, 2022
Leasehold improvements	$	17,392	$	15,983
Furniture, fixtures and equipment	5,887		5,204
Total property and equipment	23,279		21,187
Less: accumulated depreciation	(11,271)		(8,218)
Total property and equipment, net	$	12,008	$	12,969

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


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022

Research and development	$	415	$	627	$	1,231	$	1,224
Sales and marketing	48		78		141		156
General and administrative	570		295		1,681		873
Total	$	1,033	$	1,000	$	3,053	$	2,253

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Obligations under current leases	$ 5,090	$ 4,903
Marketing-related accruals	4,926	3,464
Sales and VAT tax accrual	3,045	2,396
Employee-related costs	2,678	4,233
Other	7,540	6,974
Total	$ 23,279	$ 21,970
Operating lease, liability, current, statement of financial position, [extensible enumeration]	Total	Total

PROPERTY and EQUIPMENT, net - Summary of Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Total	$ 1,033	$ 1,000	$ 3,053	$ 2,253
Research and development
Property, Plant and Equipment [Line Items]
Total	415	627	1,231	1,224
Sales and marketing
Property, Plant and Equipment [Line Items]
Total	48	78	141	156
General and administrative
Property, Plant and Equipment [Line Items]
Total	$ 570	$ 295	$ 1,681	$ 873

INCOME TAXES

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

INCOME TAXES

INCOME TAXESYear-to-date income tax expense or benefit is the product of the most current projected annual effective tax rate (“PAETR”) and the actual year-to-date pretax income (loss) adjusted for any discrete items. The income tax expense or benefit for a particular quarter, is the difference between the year-to-date calculation of income tax expense or benefit and the year-to-date calculation for the prior quarter. Items

unrelated to current period ordinary income or loss are recognized entirely in the period identified as a discrete item of tax.

The Company’s PAETR differs from the US federal statutory rate of 21.0% during the three and nine months ended September 30, 2023 and 2022 primarily due to the impact of maintaining a US valuation allowance provided on US deferred tax assets.

The Company continues to maintain a full valuation allowance on US federal and state net deferred tax assets for the period ending September 30, 2023 as a result of cumulative pre-tax losses incurred since the Company’s inception in early 2012.

The Company’s income before taxes, income tax provision or benefit and effective tax rates were as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
(In thousands, except percentages)	2023			2022			2023			2022
Income (loss) before income taxes	$	2,932		$	(18,392)		$	2,644		$	(45,422)
Provision (benefit) for income taxes	125			53			$	(1,306)		$	222
Effective tax rate	4.3		%	(0.3)		%	(49.4)		%	(0.5)		%

During the three and nine months ended September 30, 2023, the Company recognized a discrete tax benefit attributable to the excess tax benefits of stock-based compensation. This discrete benefit was the primary driver of the nine months ended September 30, 2023 tax benefit recorded as well as changes to the effective tax rate versus the prior year.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

REVENUE

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

REVENUE

The Company has three predominant sources of revenues; time-based subscriptions, in-app advertising placement by third parties, and the Duolingo English Test. 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 us and our 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 six-month or 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 Duo’s Taquería, a restaurant that opened during 2022, in the space adjacent to our 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 we receive 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.


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Revenues:
Subscription	$	105,887	$	72,172	$	287,230	$	195,376
Advertising	11,678		10,619		36,374		33,585
Duolingo English Test	10,612		8,192		30,393		24,308
Other (1)	9,447		5,082		26,127		12,402
Total revenues	$	137,624	$	96,065	$	380,124	$	265,671

________________

(1) Other revenue is mainly comprised of in-app purchases of virtual goods.

Changes in deferred revenues were as follows:


	Nine Months Ended September 30,
(In thousands)	2023		2022
Beginning balance—January 1	$	157,550	$	98,267
Amount from beginning balance recognized into revenue	(143,810)		(89,387)
Recognition of deferred revenue	(173,408)		(122,527)
Deferral of revenue	368,556		248,591
Ending balance—September 30	$	208,888	$	134,944

- 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

INTANGIBLE ASSETS AND GOODWILL - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Other intangible assets	$ 117	$ 18
Capitalized software development costs	7,170		$ 3,625
Goodwill	4,050	4,050
Goodwill, tax deductible amount	$ 3,780	$ 3,983

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net income (loss)	$ 3,950	$ (45,644)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	5,053	3,426
Stock-based compensation expense	70,219	53,188
Gain on sale of capitalized software	(100)	0
Loss on disposal of leasehold improvements	417	0
Changes in assets and liabilities:
Deferred revenue	51,338	36,677
Accounts receivable	(14,983)	2,966
Deferred cost of revenues	(11,083)	(6,039)
Prepaid expenses and other current assets	(2,299)	(2,154)
Accounts payable	1,403	(3,864)
Accrued expenses and other current liabilities	185	4,269
Noncurrent assets and liabilities	321	(777)
Net cash provided by operating activities	104,421	42,048
Cash flows from investing activities:
Capitalized software expense and purchases of intangible assets	(7,269)	(3,959)
Purchase of property and equipment	(2,267)	(5,270)
Proceeds from sale of capitalized software	100	0
Net cash used for investing activities	(9,436)	(9,229)
Cash flows from financing activities:
Proceeds from exercise of stock options	10,054	13,226
Taxes paid related to net-share settlements of share-based compensation awards	(11,482)	0
Net cash (used for) provided by financing activities	(1,428)	13,226
Net increase in cash and cash equivalents	93,557	46,045
Cash and cash equivalents - Beginning of period	608,180	553,922
Cash and cash equivalents - End of period	701,737	599,967
Supplemental disclosure of cash flow information:
Cash paid for interest	0	0
Cash paid for income taxes	2,195	608
Supplemental disclosure of noncash investing activities:
Capitalized software and purchases of intangible assets included in Current liabilities	0	8
Property and equipment included in Current liabilities	242	45
Landlord incentive included in Prepaid expenses and other current assets	$ 0	$ 2,148

INTANGIBLE ASSETS AND GOODWILL

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSETS AND GOODWILL

Intangible assets consist mostly of capitalized software, with $117 and $18 of other intangible assets as of September 30, 2023 and December 31, 2022, respectively.


(In thousands)	September 30, 2023		December 31, 2022
Intangible assets	$	23,788	$	16,827
Less: accumulated amortization	(10,022)		(8,330)
Intangible assets, net	$	13,766	$	8,497

The Company capitalized $7,170 and $3,625 of software development costs during the nine months ended September 30, 2023 and 2022, respectively. Amortization expense is included within the following financial statement line items within the Company’s Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Loss).


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Cost of revenues	$	402	$	274	$	1,207	$	547
Sales and marketing	222		208		793		626
Total	$	624	$	482	$	2,000	$	1,173

Goodwill was $4,050 at September 30, 2023 and December 31, 2022. As of September 30, 2023 and December 31, 2022, $3,780 and $3,983 of goodwill is deductible for tax purposes, respectively.

STOCK-BASED COMPENSATION

9 Months Ended

Sep. 30, 2023

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. On each January 1, the number of shares of the Company’s Class A common stock available for issuance under the 2021 Plan have been, and through January 1, 2031, will be, increased 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). On January 1, 2023, the shares available under the 2021 Plan and ESPP were increased by 2,018 shares and 319 shares, respectively.

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, 2023	4,410	$	14.04	6.25	$	251,832
Granted (1)	—
Exercised	(1,068)	9.46

Forfeited and expired	(28)	13.84
Options outstanding at September 30, 2023	3,314	$	15.52	5.79	$	499,576
Options exercisable at September 30, 2023	3,042	$	14.94	5.70	$	459,149

________________

(1) There were no stock options granted during the nine months ended September 30, 2023.

The total intrinsic value of options exercised was approximately $127,785 and $129,725 for the periods ended September 30, 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, 2023	2,036	$	85.74
Granted	803	132.05
Released	(447)	90.07
Forfeited	(169)	95.57
Outstanding at September 30, 2023	2,223	$	100.86

As of September 30, 2023, there was approximately $2,288 of unrecognized compensation cost related to stock options granted under the plans with a weighted-average period of approximately one year. The amount of unrecognized compensation expense for RSUs as of September 30, 2023 was $207,260 with a weighted-average period of approximately three years. Total unrecognized compensation expense as of September 30, 2023 was $209,548.

There were 9,433 shares available for grant at September 30, 2023.

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 completion 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-prices hurdle 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	$	127.50	90
2	$	153.00	90
3	$	178.50	90
4	$	204.00	180
5	$	255.00	180
6	$	306.00	180
7	$	357.00	180
8	$	408.00	180
9	$	612.00	270
10	$	816.00	360

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 and 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 stock-price hurdles for the first two tranches were met during 2021. With respect to these two tranches in combination, the service-based condition was satisfied during the three months ended September 30, 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, which shares were added to the shares of Class A common stock available for issuance under the 2021 Plan. As of the date of this Quarterly Report on Form 10-Q, no additional stock-price hurdles have been met. The Company recognized $6,595 and $20,829 of stock-based compensation expense related to these awards for the three and nine months ended September 30, 2023, respectively, and $7,572 and $23,699 for the three and nine months ended September 30, 2022, respectively, which is included within General and administrative in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Loss). As of September 30, 2023, there is $42,527 of unrecognized compensation expense related to these awards.

Total stock-based compensation expense was $25,432 and $70,219 for the three and nine months ended September 30, 2023, respectively, and $20,488 and $53,188 for the three and nine months ended September 30, 2022, respectively.

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


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Cost of revenues	$	15	$	11	$	40	$	27
Research and development	12,244		8,030		32,568		17,435
Sales and marketing	1,151		786		2,899		1,729
General and administrative	12,022		11,661		34,712		33,997
Total	$	25,432	$	20,488	$	70,219	$	53,188

Nominal amounts of stock based compensation expense is capitalized into intangible assets for the three and nine months ended September 30, 2023 and 2022.

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Sep. 30, 2023	Dec. 31, 2022
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)	35,726	31,899
Common stock, shares outstanding (in shares)	35,726	31,899
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)	6,246	8,462
Common stock, shares outstanding (in shares)	6,246	8,462

DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION (Details)	Sep. 30, 2023 language
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of languages, more than	40

REVENUE - Narrative (Details)	Sep. 30, 2023 sourceOfRevenue user
Disaggregation of Revenue [Line Items]
Number of sources of revenue \| sourceOfRevenue	3
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
Minimum
Disaggregation of Revenue [Line Items]
Subscription period (in years)	6 months
Maximum
Disaggregation of Revenue [Line Items]
Subscription period (in years)	1 year

- 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

DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION	9 Months Ended
DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION	Sep. 30, 2023
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 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 United States, China and Germany. 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 United States (“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, 2023 and 2022. Unless otherwise specified, all dollar amounts (other than per share amounts) are referred to in thousands. 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 consistently applied the accounting policies consistent with the annual Unaudited Condensed Consolidated Financial Statements elsewhere in this Quarterly Report on Form 10-Q, in preparing these Unaudited Condensed Consolidated Financial Statements. 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, 2022 included in the Annual Report on Form 10-K and filed with the SEC.

EMPLOYEE BENEFIT PLAN	9 Months Ended
EMPLOYEE BENEFIT PLAN	Sep. 30, 2023
Postemployment Benefits [Abstract]
EMPLOYEE BENEFIT PLAN	EMPLOYEE BENEFIT PLANThe 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 $1,563 and $4,433 for the three and nine months ended September 30, 2023, respectively, and $1,097 and $3,139 for the three and nine months ended September 30, 2022, respectively. The Company did not make any discretionary matching or profit sharing contributions during the three and nine months ended September 30, 2023 and 2022.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 701,737	$ 608,180
Cash
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	63,322	91,189
Money market funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 638,415	$ 516,991

REVENUE - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 137,624	$ 96,065	$ 380,124	$ 265,671
Transferred over Time \| Subscription
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	105,887	72,172	287,230	195,376
Transferred over Time \| Advertising
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	11,678	10,619	36,374	33,585
Transferred over Time \| Duolingo English Test
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	10,612	8,192	30,393	24,308
Transferred over Time \| Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 9,447	$ 5,082	$ 26,127	$ 12,402

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479941/924-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2023	Nov. 07, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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 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	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		35,797,739
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		6,216,077

REVENUE (Tables)

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Schedule of Revenue Sources and Streams


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Revenues:
Subscription	$	105,887	$	72,172	$	287,230	$	195,376
Advertising	11,678		10,619		36,374		33,585
Duolingo English Test	10,612		8,192		30,393		24,308
Other (1)	9,447		5,082		26,127		12,402
Total revenues	$	137,624	$	96,065	$	380,124	$	265,671

________________

(1) Other revenue is mainly comprised of in-app purchases of virtual goods.

Schedule of Deferred Revenues

Changes in deferred revenues were as follows:


	Nine Months Ended September 30,
(In thousands)	2023		2022
Beginning balance—January 1	$	157,550	$	98,267
Amount from beginning balance recognized into revenue	(143,810)		(89,387)
Recognition of deferred revenue	(173,408)		(122,527)
Deferral of revenue	368,556		248,591
Ending balance—September 30	$	208,888	$	134,944

INTANGIBLE ASSETS AND GOODWILL - Capitalized Software (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets	$ 23,788	$ 16,827
Less: accumulated amortization	(10,022)	(8,330)
Intangible assets, net	$ 13,766	$ 8,497

EARNINGS (LOSS) PER SHARE

9 Months Ended

Sep. 30, 2023

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 (loss) 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.


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands, except per share data)	2023		2022		2023		2022
Numerator:
Net income (loss) attributable to Class A and Class B common stockholders	$	2,807	$	(18,445)	$	3,950	$	(45,644)


Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, basic and diluted	41,719		39,753		41,190		39,210
Effect of dilutive securities

Dilutive effect of stock options outstanding (1)	3,004		—		3,004		—
RSUs outstanding	2,223		—		2,223		—
Denominator for dilutive net income per common share - weighted-average shares	46,946		39,753		46,417		39,210
Basic income (loss) per common share	$	0.07	$	(0.46)	$	0.10	$	(1.16)
Diluted income (loss) per common share	$	0.06	$	(0.46)	$	0.09	$	(1.16)

________________

(1) The Company had 3.3 million options outstanding as of September 30, 2023. 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 three and nine months ended September 30, 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:



(In thousands)																		September 30, 2022

Founder awards where performance has been met																		180
Stock options outstanding (1)																		4,575
RSUs outstanding (1)																		1,854
Total																		6,609

________________

(1) Prior year amounts were adjusted in the current year table to include unvested options and RSUs.

Founder awards of 1,620, where the performance criteria has not been satisfied, are excluded from the above tables because the stock-price hurdles for those awards had not been met as of September 30, 2023.

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net income (loss) attributable to Class A and Class B common stockholders	$ 2,807	$ (18,445)	$ 3,950	$ (45,644)

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-8

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-9

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-4

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480167/946-830-55-10

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483581/946-220-45-7

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(9))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(1)(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-3

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 20: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-60B

Reference 32: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483499/205-20-50-7

Reference 35: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Concentration Risk [Line Items]
Advertising costs	$ 16,229	$ 12,807	$ 39,528	$ 34,354
Accounts Receivable \| Customer Concentration Risk \| Apple
Concentration Risk [Line Items]
Concentration risk (in percent)			67.20%		56.20%
Accounts Receivable \| Customer Concentration Risk \| Google
Concentration Risk [Line Items]
Concentration risk (in percent)			18.10%		27.50%
Accounts Receivable \| Customer Concentration Risk \| Stripe
Concentration Risk [Line Items]
Concentration risk (in percent)			10.20%
Revenue from Contract with Customer Benchmark \| Customer Concentration Risk \| Apple
Concentration Risk [Line Items]
Concentration risk (in percent)	59.30%	55.20%	58.30%	53.40%
Revenue from Contract with Customer Benchmark \| Customer Concentration Risk \| Google
Concentration Risk [Line Items]
Concentration risk (in percent)	24.90%	27.70%	25.70%	28.40%
Revenue from Contract with Customer Benchmark \| Customer Concentration Risk \| Stripe
Concentration Risk [Line Items]
Concentration risk (in percent)	12.60%		12.10%

INTANGIBLE ASSETS AND GOODWILL (Tables)

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets

Intangible assets consist mostly of capitalized software, with $117 and $18 of other intangible assets as of September 30, 2023 and December 31, 2022, respectively.


(In thousands)	September 30, 2023		December 31, 2022
Intangible assets	$	23,788	$	16,827
Less: accumulated amortization	(10,022)		(8,330)
Intangible assets, net	$	13,766	$	8,497

Finite-lived Intangible Assets Amortization Expense

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


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Cost of revenues	$	402	$	274	$	1,207	$	547
Sales and marketing	222		208		793		626
Total	$	624	$	482	$	2,000	$	1,173

INCOME TAXES (Tables)

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

The Company’s income before taxes, income tax provision or benefit and effective tax rates were as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
(In thousands, except percentages)	2023			2022			2023			2022
Income (loss) before income taxes	$	2,932		$	(18,392)		$	2,644		$	(45,422)
Provision (benefit) for income taxes	125			53			$	(1,306)		$	222
Effective tax rate	4.3		%	(0.3)		%	(49.4)		%	(0.5)		%

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES

9 Months Ended

Sep. 30, 2023

Other Liabilities Disclosure [Abstract]

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES

Accrued expenses and other current liabilities consisted of the following:


(In thousands)	September 30, 2023		December 31, 2022
Obligations under current leases	$	5,090	$	4,903
Marketing-related accruals	4,926		3,464
Sales and VAT tax accrual	3,045		2,396
Employee-related costs	2,678		4,233
Other	7,540		6,974
Total	$	23,279	$	21,970

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

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

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, common stock valuation, operating lease right-of-use assets and liabilities, capitalization of internally developed software and associated useful lives and contingent liabilities. 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.

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. The following table shows the breakout between cash and money market funds.



(In thousands)	September 30, 2023		December 31, 2022
Cash	$	63,322	$	91,189
Money market funds	638,415		516,991
Total	$	701,737	$	608,180

The Money market funds are considered Level 1 financial assets. Level 1 financial assets use inputs that are the unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Advertising Costs— Advertising costs were approximately $16,229 and $39,528 for the three and nine months ended September 30, 2023, respectively, and $12,807 and $34,354 for the three and nine months ended September 30, 2022, respectively, and are included within Sales and marketing in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Loss).

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—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 three service providers, Apple, Google, and Stripe accounted for 67.2%, 18.1%, and 10.2% of total Accounts receivable as of September 30, 2023, respectively. The top two service providers, Apple and Google, accounted for 56.2% and 27.5% of total Accounts receivable as of December 31, 2022, respectively.

Three service providers, Apple, Google and Stripe, processed 59.3%, 24.9%, and 12.6%, and 58.3%, 25.7% and 12.1% of total Revenues for the three and nine months ended September 30, 2023, respectively. Two services providers, Apple and Google, processed 55.2% and 27.7%, and 53.4% and 28.4% of total Revenues for the three and nine months ended September 30, 2022, respectively.

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. No assets were impaired during the three and nine months ended September 30, 2023 and 2022.

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.

Recently Adopted Accounting Pronouncements

There are no recently adopted accounting pronouncements.

EARNINGS (LOSS) PER SHARE - Schedule of Antidilutive Securities (Details) shares in Thousands	9 Months Ended
	Sep. 30, 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)	6,609
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
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)	4,575
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)	1,854

STOCK-BASED COMPENSATION - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Number of options
Options outstanding, beginning balance (in shares) \| shares	4,410,000
Granted (in shares) \| shares	0
Exercised (in shares) \| shares	(1,068,000)
Forfeited and expired (in shares) \| shares	(28,000)
Options outstanding, ending balance (in shares) \| shares	3,314,000	4,410,000
Number of options exercisable (in shares) \| shares	3,042,000
Weighted- average exercise price
Outstanding, beginning balance (in usd per share) \| $ / shares	$ 14.04
Granted (in usd per share) \| $ / shares
Exercised (in usd per share) \| $ / shares	9.46
Forfeited and expired (in usd per share) \| $ / shares	13.84
Outstanding, ending balance (in usd per share) \| $ / shares	15.52	$ 14.04
Weighted average exercise price, options exercisable (in usd per share) \| $ / shares	$ 14.94
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term (in years), outstanding	5 years 9 months 14 days	6 years 3 months
Weighted average remaining contractual term (in years), exercisable	5 years 8 months 12 days
Aggregate intrinsic value, outstanding \| $	$ 499,576	$ 251,832
Aggregate intrinsic value, exercisable \| $	$ 459,149

INTANGIBLE ASSETS AND GOODWILL - Schedule of Capitalized Software Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Finite-Lived Intangible Assets [Line Items]
Amortization of capitalized computer software	$ 624	$ 482	$ 2,000	$ 1,173
Cost of revenues
Finite-Lived Intangible Assets [Line Items]
Amortization of capitalized computer software	402	274	1,207	547
Sales and marketing
Finite-Lived Intangible Assets [Line Items]
Amortization of capitalized computer software	$ 222	$ 208	$ 793	$ 626

EMPLOYEE BENEFIT PLAN (Details) - USD ($)	3 Months Ended		9 Months Ended
EMPLOYEE BENEFIT PLAN (Details) - USD ($)	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, contributions by employer	$ 1,563,000	$ 1,097,000	$ 4,433,000	$ 3,139,000
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%

EARNINGS (LOSS) PER SHARE - Narrative (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2023 votePerShare shares
Performance Based RSUs
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

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 701,737	$ 608,180
Accounts receivable	61,711	46,728
Deferred cost of revenues	46,124	35,041
Prepaid expenses and other current assets	9,533	7,234
Total current assets	819,105	697,183
Property and equipment, net	12,008	12,969
Goodwill	4,050	4,050
Intangible assets, net	13,766	8,497
Operating lease right-of-use assets	19,901	22,508
Deferred tax assets, net	633	633
Other assets	1,251	1,507
Total assets	870,714	747,347
Current liabilities
Accounts payable	2,712	1,177
Deferred revenues	208,888	157,550
Income tax payable	55	1,069
Accrued expenses and other current liabilities	23,279	21,970
Total current liabilities	234,934	181,766
Long-term obligation under operating leases	20,961	23,503
Total liabilities	255,895	205,269
Commitments and contingencies (Note 8)
Stockholders’ equity
Class A common stock, $0.0001 par value; 2,000,000 shares authorized as of September 30, 2023 and December 31, 2022; 35,726 and 31,899 issued and outstanding at September 30, 2023 and December 31, 2022, respectively Class B common stock, $0.0001 par value; 30,000 shares authorized as of September 30, 2023 and December 31, 2022; 6,246 and 8,462 issued and outstanding at September 30, 2023 and December 31, 2022, respectively	4	4
Additional paid-in capital	841,353	772,562
Accumulated deficit	(226,538)	(230,488)
Total stockholders’ equity	614,819	542,078
Total liabilities and stockholders' equity	$ 870,714	$ 747,347

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 01, 2023 shares	Jan. 01, 2022	Jun. 30, 2021 USD ($) tranche day $ / shares shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) shares	Sep. 30, 2022 USD ($)	Dec. 31, 2021 tranche	Jul. 26, 2021 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)						0
Aggregate intrinsic value, exercised \| $						$ 127,785	$ 129,725
Unrecognized compensation cost, options \| $				$ 2,288		2,288
Unrecognized compensation cost \| $				209,548		209,548
Closing trading price, specified calendar day \| day			60
Compensation expense \| $				25,432	$ 20,488	70,219	53,188
Stock-based compensation expense \| $				$ 25,432	20,488	$ 70,219	53,188
Stock options outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, weighted-average period of recognition (in years)						1 year
Number of options available for grant (in shares)				9,433,000		9,433,000
RSUs outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, weighted-average period of recognition (in years)						3 years
Unrecognized compensation expense, excluding options \| $				$ 207,260		$ 207,260
Equity instruments other than options, grants in period (in shares)						803,000
Performance Based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, excluding options \| $				42,527		$ 42,527
Performance Based RSUs \| 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $				$ 6,595	$ 7,572	$ 20,829	$ 23,699
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)			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 \| Founders \| Tranche One and Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of tranches \| tranche								2
Release of performance stock units (in shares)				180,000
Shares disbursed to founders in net-share settlement (in shares)				96,000
Shares withheld for taxes (in shares)				84,000
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)									7,946,000
Share-based compensation, shares outstanding increase, maximum amount (in percent)		5.00%
Additional shares authorized (in shares)	2,018,000
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)									1,119,000
Additional shares authorized (in shares)	319,000
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)						0

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2023
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 United States (“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, 2023 and 2022. Unless otherwise specified, all dollar amounts (other than per share amounts) are referred to in thousands.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, common stock valuation, operating lease right-of-use assets and liabilities, capitalization of internally developed software and associated useful lives and contingent liabilities. 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.
Cash and Cash Equivalents	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.The Money market funds are considered Level 1 financial assets. Level 1 financial assets use inputs that are the unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.
Advertising Costs	Advertising Costs— Advertising costs were approximately $16,229 and $39,528 for the three and nine months ended September 30, 2023, respectively, and $12,807 and $34,354 for the three and nine months ended September 30, 2022, respectively, and are included within Sales and marketing in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Loss).
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 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.
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.
Recently Issued Pronouncements Not Yet Adopted and Recently Adopted Accounting Pronouncements	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. Recently Adopted Accounting Pronouncements There are no recently adopted accounting pronouncements.
Revenue	REVENUE The Company has three predominant sources of revenues; time-based subscriptions, in-app advertising placement by third parties, and the Duolingo English Test. 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 us and our 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 six-month or 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 Duo’s Taquería, a restaurant that opened during 2022, in the space adjacent to our 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 we receive 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.

UNAUDITED CONDENSED 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	53,188		53,188
Stock options exercised (in shares)		1,585
Stock options exercised	13,226		13,226
Release of restricted stock units (in shares)		229
Net income (loss)	(45,644)			(45,644)
Ending balance (in shares) at Sep. 30, 2022		40,086
Ending balance at Sep. 30, 2022	533,826	$ 4	750,380	(216,558)
Beginning balance (in shares) at Jun. 30, 2022		39,587
Beginning balance at Jun. 30, 2022	528,219	$ 4	726,328	(198,113)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	20,488		20,488
Stock options exercised (in shares)		379
Stock options exercised	3,564		3,564
Release of restricted stock units (in shares)		120
Net income (loss)	(18,445)			(18,445)
Ending balance (in shares) at Sep. 30, 2022		40,086
Ending balance at Sep. 30, 2022	533,826	$ 4	750,380	(216,558)
Beginning balance (in shares) at Dec. 31, 2022		40,361
Beginning balance at Dec. 31, 2022	542,078	$ 4	772,562	(230,488)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	70,219		70,219
Release of performance stock units (in shares)		180
Taxes paid related to net-share settlements of share-based compensation awards ( in shares)		(84)
Taxes paid related to net-share settlements of share-based compensation awards	$ (11,482)		(11,482)
Stock options exercised (in shares)	1,068	1,068
Stock options exercised	$ 10,054		10,054
Release of restricted stock units (in shares)		447
Net income (loss)	3,950			3,950
Ending balance (in shares) at Sep. 30, 2023		41,972
Ending balance at Sep. 30, 2023	614,819	$ 4	841,353	(226,538)
Beginning balance (in shares) at Jun. 30, 2023		41,531
Beginning balance at Jun. 30, 2023	596,405	$ 4	825,746	(229,345)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Stock-based compensation expense	25,432		25,432
Release of performance stock units (in shares)		180
Taxes paid related to net-share settlements of share-based compensation awards ( in shares)		(84)
Taxes paid related to net-share settlements of share-based compensation awards	(11,482)		(11,482)
Stock options exercised (in shares)		152
Stock options exercised	1,657		1,657
Release of restricted stock units (in shares)		193
Net income (loss)	2,807			2,807
Ending balance (in shares) at Sep. 30, 2023		41,972
Ending balance at Sep. 30, 2023	$ 614,819	$ 4	$ 841,353	$ (226,538)

Insider Trading Arrangements	3 Months Ended	9 Months Ended
Insider Trading Arrangements	Sep. 30, 2023 shares	Sep. 30, 2023 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Terminated	false
Natalie Glance [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On September 5, 2023, 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 which provides for the sale of up to 60,000 shares of the Company’s Class A common stock. The Glance 10b5-1 Sales Plan will remain in effect until the earlier of (1) December 31, 2024, (2) the date on which an aggregate of 60,000 shares of the Company’s Class A common stock have been sold under the Glance 10b5-1 Sales Plan, or (3) such time as the Glance 10b5-1 Sales Plan is otherwise terminated or expires according to its terms.
Name	Natalie Glance
Title	Chief Engineering Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 5, 2023
Arrangement Duration	483 days
Aggregate Available	60,000	60,000
Robert Meese, [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On September 8, 2023, 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) under the Exchange Act which provides for the sale of up to 40,000 shares of the Company’s Class A common stock. The Meese 10b5-1 Sales Plan will remain in effect until the earlier of (1) October 31, 2024, (2) the date on which an aggregate of 40,000 shares of the Company’s common stock have been sold under the Meese 10b5-1 Sales Plan, or (3) such time as the Meese 10b5-1 Sales Plan is otherwise terminated or expires according to its terms.
Name	Robert Meese
Title	Chief Business Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 8, 2023
Arrangement Duration	419 days
Aggregate Available	40,000	40,000
Stephen Chen [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On September 11, 2023, the 10b5-1 sales plan intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act entered into by Stephen Chen, General Counsel, on June 2, 2023 expired in accordance with its terms upon the sale of the maximum aggregate number of shares of Class A common stock covered by such plan. On September 15, 2023, Mr. Chen entered into a 10b5-1 sales plan (the “Chen 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act which provides for 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. The Chen 10b5-1 Sales Plan will remain in effect until the earlier of (1) July 31, 2024, (2) the date on which an aggregate of 20,000 shares of the Company’s Class A common stock have been sold under the Chen 10b5-1 Sales Plan, or (3) such time as the Chen 10b5-1 Sales Plan is otherwise terminated or expires according to its terms.
Aggregate Available	20,000	20,000
Stephen Chen June 2023 Plan [Member] \| Stephen Chen [Member]
Trading Arrangements, by Individual
Name	Stephen Chen
Title	General Counsel
Adoption Date	June 2, 2023
Rule 10b5-1 Arrangement Terminated	true
Termination Date	September 11, 2023
Stephen Chen September 2023 Plan [Member] \| Stephen Chen [Member]
Trading Arrangements, by Individual
Name	Stephen Chen
Title	General Counsel
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 15, 2023
Arrangement Duration	320 days
Aggregate Available	20,000	20,000

EARNINGS (LOSS) PER SHARE - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Numerator:
Net income (loss) attributable to Class A and Class B common stockholders	$ 2,807	$ (18,445)	$ 3,950	$ (45,644)
Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, diluted (in shares)	46,946	39,753	46,417	39,210
Effect of dilutive securities
Basic loss per common share (in usd per share)	$ 0.07	$ (0.46)	$ 0.10	$ (1.16)
Diluted loss per common share (in usd per share)	$ 0.06	$ (0.46)	$ 0.09	$ (1.16)
Options outstanding (in shares)	3,314		3,314		4,410
Stock options outstanding
Effect of dilutive securities
Stock options and RSUs outstanding (in shares)	3,004	0	3,004	0
RSUs outstanding
Effect of dilutive securities
Stock options and RSUs outstanding (in shares)	2,223	0	2,223	0
Class A and Class B Common Stock
Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, basic (in shares)	41,719	39,753	41,190	39,210
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, diluted (in shares)	41,719	39,753	41,190	39,210

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Schedule of Cash and Cash Equivalents

The following table shows the breakout between cash and money market funds.



(In thousands)	September 30, 2023		December 31, 2022
Cash	$	63,322	$	91,189
Money market funds	638,415		516,991
Total	$	701,737	$	608,180

EARNINGS (LOSS) PER SHARE (Tables)

9 Months Ended

Sep. 30, 2023

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 (loss) 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.


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands, except per share data)	2023		2022		2023		2022
Numerator:
Net income (loss) attributable to Class A and Class B common stockholders	$	2,807	$	(18,445)	$	3,950	$	(45,644)


Denominator:
Weighted-average shares in computing net income (loss) per share attributable to Class A and Class B common stockholders, basic and diluted	41,719		39,753		41,190		39,210
Effect of dilutive securities

Dilutive effect of stock options outstanding (1)	3,004		—		3,004		—
RSUs outstanding	2,223		—		2,223		—
Denominator for dilutive net income per common share - weighted-average shares	46,946		39,753		46,417		39,210
Basic income (loss) per common share	$	0.07	$	(0.46)	$	0.10	$	(1.16)
Diluted income (loss) per common share	$	0.06	$	(0.46)	$	0.09	$	(1.16)

________________

Schedule of Antidilutive Securities Excluded from Computation of Earnings 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:



(In thousands)																		September 30, 2022

Founder awards where performance has been met																		180
Stock options outstanding (1)																		4,575
RSUs outstanding (1)																		1,854
Total																		6,609

________________

(1) Prior year amounts were adjusted in the current year table to include unvested options and RSUs.

SUBSEQUENT EVENTS	9 Months Ended
SUBSEQUENT EVENTS	Sep. 30, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTSNone.

STOCK-BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

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, 2023	4,410	$	14.04	6.25	$	251,832
Granted (1)	—
Exercised	(1,068)	9.46

Forfeited and expired	(28)	13.84
Options outstanding at September 30, 2023	3,314	$	15.52	5.79	$	499,576
Options exercisable at September 30, 2023	3,042	$	14.94	5.70	$	459,149

________________

(1) There were no stock options granted during the nine months ended September 30, 2023.

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, 2023	2,036	$	85.74
Granted	803	132.05
Released	(447)	90.07
Forfeited	(169)	95.57
Outstanding at September 30, 2023	2,223	$	100.86

Share-based Payment Arrangement, Payment Award


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

Share-based Payment Arrangement, Expensed, Amount

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


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Cost of revenues	$	15	$	11	$	40	$	27
Research and development	12,244		8,030		32,568		17,435
Sales and marketing	1,151		786		2,899		1,729
General and administrative	12,022		11,661		34,712		33,997
Total	$	25,432	$	20,488	$	70,219	$	53,188

STOCK-BASED COMPENSATION - Schedule of Payment Award (Details) - RSUs outstanding shares in Thousands	Jun. 30, 2021 $ / shares shares
1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 127.50
Number of RSUs Eligible to Vest (in shares) \| shares	90
2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 153.00
Number of RSUs Eligible to Vest (in shares) \| shares	90
3
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 178.50
Number of RSUs Eligible to Vest (in shares) \| shares	90
4
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 204.00
Number of RSUs Eligible to Vest (in shares) \| shares	180
5
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 255.00
Number of RSUs Eligible to Vest (in shares) \| shares	180
6
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 306.00
Number of RSUs Eligible to Vest (in shares) \| shares	180
7
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 357.00
Number of RSUs Eligible to Vest (in shares) \| shares	180
8
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 408.00
Number of RSUs Eligible to Vest (in shares) \| shares	180
9
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 612.00
Number of RSUs Eligible to Vest (in shares) \| shares	270
10
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Stock Price Hurdle (in usd per share) \| $ / shares	$ 816.00
Number of RSUs Eligible to Vest (in shares) \| shares	360

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)

9 Months Ended

Sep. 30, 2023

Other Liabilities Disclosure [Abstract]

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:


(In thousands)	September 30, 2023		December 31, 2022
Obligations under current leases	$	5,090	$	4,903
Marketing-related accruals	4,926		3,464
Sales and VAT tax accrual	3,045		2,396
Employee-related costs	2,678		4,233
Other	7,540		6,974
Total	$	23,279	$	21,970

PROPERTY and EQUIPMENT, net - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 23,279	$ 21,187
Less: accumulated depreciation	(11,271)	(8,218)
Total property and equipment, net	12,008	12,969
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	17,392	15,983
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 5,887	$ 5,204

STOCK-BASED COMPENSATION - Schedule of Restricted Stock Unit Activity (Details) - RSUs outstanding - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Restricted stock units
Beginning balance (in shares)	2,223	2,036
Granted (in shares)	803
Released (in shares)	(447)
Forfeited (in shares)	(169)
Ending balance (in shares)	2,223
Weighted- average grant date fair value per share
Beginning balance (in usd per share)	$ 85.74
Granted (in usd per share)	132.05
Released (in usd per share)	90.07
Forfeited (in usd per share)	95.57
Ending balance (in usd per share)	$ 100.86

PROPERTY and EQUIPMENT, net (Tables)

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property and equipment consists of the following as of September 30, 2023 and December 31, 2022:



(In thousands)	September 30, 2023		December 31, 2022
Leasehold improvements	$	17,392	$	15,983
Furniture, fixtures and equipment	5,887		5,204
Total property and equipment	23,279		21,187
Less: accumulated depreciation	(11,271)		(8,218)
Total property and equipment, net	$	12,008	$	12,969

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


	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022

Research and development	$	415	$	627	$	1,231	$	1,224
Sales and marketing	48		78		141		156
General and administrative	570		295		1,681		873
Total	$	1,033	$	1,000	$	3,053	$	2,253

STOCK-BASED COMPENSATION - Schedule of Income Statement Location for Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 25,432	$ 20,488	$ 70,219	$ 53,188
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	15	11	40	27
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	12,244	8,030	32,568	17,435
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	1,151	786	2,899	1,729
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 12,022	$ 11,661	$ 34,712	$ 33,997

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(02)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Revenues	$ 137,624	$ 96,065	$ 380,124	$ 265,671
Cost of revenues	36,254	26,302	101,534	71,661
Gross profit	101,370	69,763	278,590	194,010
Operating expenses:
Research and development	50,305	41,976	144,096	105,974
Sales and marketing	22,335	17,721	56,670	47,938
General and administrative	33,400	30,228	95,878	87,141
Total operating expenses	106,040	89,925	296,644	241,053
Loss from operations	(4,670)	(20,162)	(18,054)	(47,043)
Other expense, net of other income	(1,023)	(490)	(1,109)	(1,341)
Loss before interest income and income taxes	(5,693)	(20,652)	(19,163)	(48,384)
Interest income	8,625	2,260	21,807	2,962
Income (loss) before income taxes	2,932	(18,392)	2,644	(45,422)
Provision (benefit) for income taxes	125	53	(1,306)	222
Net income (loss)	2,807	(18,445)	3,950	(45,644)
Net comprehensive income (loss)	$ 2,807	$ (18,445)	$ 3,950	$ (45,644)
Net income (loss) per share attributable to Class A and Class B common stockholders, basic (in usd per share)	$ 0.07	$ (0.46)	$ 0.10	$ (1.16)
Net income (loss) per share attributable to Class A and Class B common stockholders, diluted (in usd per share)	$ 0.06	$ (0.46)	$ 0.09	$ (1.16)

INCOME TAXES - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ 2,932	$ (18,392)	$ 2,644	$ (45,422)
Provision (benefit) for income taxes	$ 125	$ 53	$ (1,306)	$ 222
Effective income tax rate	4.30%	(0.30%)	(49.40%)	(0.50%)

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(11))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479557/942-235-S99-1

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-SubTopic 20
-Topic 940
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481913/940-20-25-1

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

COMMITMENTS AND CONTINGENCIES	9 Months Ended
COMMITMENTS AND CONTINGENCIES	Sep. 30, 2023
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 three and nine months ended September 30, 2023 and 2022.

REVENUE - Deferred Revenue Rollforward (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Revenue from Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 157,550	$ 98,267
Amount from beginning balance recognized into revenue	(143,810)	(89,387)
Recognition of deferred revenue	(173,408)	(122,527)
Deferral of revenue	368,556	248,591
Ending balance	$ 208,888	$ 134,944