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Case studies/No. 002Education technology · United States
Duolingo

Duolingo went AI-first: far more courses, slower growth

PublishedOctober 23, 2026
Facts as ofOctober 23, 2026
Reading time4 min
Score6 / 10
Download PDF 4 pages · 0.1 MB

At a glance

Duolingo told its staff and the public it would stop paying contractors for work AI can do, and would build its courses with AI. In plain words: AI writes the first draft of each lesson, and a smaller group of people checks it before learners see it.

Our verdict6/10Our score is 6 out of 10. The courses came far faster and the business kept growing, but within a year that growth slowed a lot, and nobody has shown whether the public backlash caused it.
01

What they did

CEO Luis von Ahn's memo said the change would come gradually[1]. In the memo, dated April 2025, von Ahn added that teams would get new hires only if they could not automate more of their own work[2]. The shift was not new: Duolingo confirmed it had already cut about 10% of its contractors at the end of 2023[3]. The memo put in writing a change that was under way. The reason was speed. Von Ahn said the first 100 courses took about 12 years to build[4]. With AI, Duolingo launched 148 new ones in less than a year[4].

Course units Duolingo published per quarter: about 1,800 per quarter in 2024, and 20,500 from January to March 2026.
Fig. 1. Course units published per quarter, from Duolingo's own report to its shareholders.[5]
02

What they got so far

From January to March 2026, Duolingo published 20,500 course units, many times its pace in 2024.[5] From April to June 2026, sales were 18% higher than a year before.[6] 2025 was a record year, with sales of $1,037.6 million, up 39%.[7]

Duolingo's sales, growth on the year: 41% from April to June 2025, 27% from January to March 2026, 18% from April to June 2026.
Fig. 2. Sales growth on the year, quarter by quarter, from Duolingo's filings.[5][6]

By June 2026, 23% more people used the app each day than a year earlier, well below its earlier pace.[6] The cost: by mid-2026, Duolingo's own measure of profit fell to 25.9% of sales, which the company called a deliberate spend to win users.[6] No full-time staff were let go, von Ahn says[8]: Duolingo had more than 900 employees in 2025.[9]

Luis von Ahn, the CEO, admits user growth slowed toward the end of 2025.[10] Duolingo blames its own focus on charging users more, not the memo.[7] Von Ahn said he gave too little context in the memo.[8] Duolingo then dropped AI use from staff reviews.[10] By mid-2026, Duolingo listed relying on AI suppliers among its business risks.[6]

Morgan Stanley saw US users fall after the backlash, with no drop abroad.[11] Jefferies said the dip could be tied to Luis von Ahn's memo.[12] The Motley Fool tied the 2025 share price drop to the company's forecast and a strategic shift instead.[13] On quality there are only stories: a current worker told The Washington Post the AI content falls short of the company's standard.[14] Benjamin Costello, a fired contractor, found "tons and tons of errors."[14] A learner of French found the AI stories wrong at times, and nobody has measured it.[15]

Our view: Duolingo got the speed it promised and kept growing, and the slowdown is real, but its cause is not settled; the backlash may have cost users, and nobody has shown it did.

Growth on the year in people using Duolingo each day: 40% in June 2025, 36% in September 2025, 30% in December 2025, 21% in March 2026 and 23% in June 2026.
Fig. 3. People using the app each day, growth on the year, from Duolingo's filings.[7][5][6]
03

Our score

6/10

Confidence: medium.

A 10 would be faster gains in sales and profit, courses ready in weeks, and users, staff and brand all intact. Duolingo got the speed and kept its staff, but the business has since lost much of its momentum, a grade that rests on the company's filed results, not on whether the backlash was to blame.

What we don't know

Each open question, and how its answer would move the score.

  1. Why new users stopped arriving as fast.If the backlash drove them away, the score falls; if its own push to earn more per user did, it rises.
  2. Whether the AI-made courses teach as well as the old ones.Learner results as good or better would raise the score; worse results would lower it.
  3. How much the company saved on contractors.A disclosed drop in what it spends on making content would raise the score.
  4. Whether today's pace is a pause or the new normal.A pickup would raise the score; a further fall would lower it.
04

What it means for your business

If you pay freelancers to write or translate, this is the part of Duolingo's move you can copy: AI writes the first draft. The draft is only as good as the person who checks it, and announcing the change loudly can cost you goodwill. One person who reads both languages well has to own it, reviewing every piece before a customer sees it, about 1 to 4 hours a week[16]. For 50,000 words a year, freelancers cost about $4,000 to $15,000 and AI tools plus paid checking about $950 to $7,500, usually cheaper but not always, with nothing to build[17][18]. This week, run a month of your copy through an AI tool, have your checker time the review, and compare the total with your last freelancer invoice before you tell anyone.

05

Sources

  1. [1]
    Duolingo's CEO lays out 5 ways AI will be used to decide the future of its workforce. AOL (Business Insider) https://www.aol.com/duolingos-ceo-lays-3-ways-040735775.htmlApril 29, 2025
  2. [2]
    Duolingo launches 148 courses created with AI. TechCrunch https://techcrunch.com/2025/04/30/duolingo-launches-148-courses-created-with-ai-after-sharing-plans-to-replace-contractors-with-aiApril 30, 2025
  3. [3]
    Duolingo cut 10% of its contractor workforce as the company embraces AI. TechCrunch https://techcrunch.com/2024/01/09/duolingo-cut-10-of-its-contractor-workforce-as-the-company-embraces-aiJanuary 9, 2024
  4. [4]
    Duolingo Launches 148 New Language Courses. Duolingo investor relations https://investors.duolingo.com/news-releases/news-release-details/duolingo-launches-148-new-language-coursesApril 30, 2025
  5. [5]
    Duolingo shareholder letter Q1 2026. Duolingo (SEC Form 8-K exhibit) https://www.sec.gov/Archives/edgar/data/0001562088/000162828026029790/q1fy26duolingo3-31x26share.htmMay 4, 2026
  6. [6]
    Duolingo shareholder letter Q2 2026. Duolingo (SEC Form 8-K exhibit) https://www.sec.gov/Archives/edgar/data/0001562088/000162828026053299/q2fy26duolingo6-30x26share.htmAccessed October 23, 2026
  7. [7]
    Duolingo shareholder letter Q4 / FY 2025. Duolingo (SEC Form 8-K exhibit) https://www.sec.gov/Archives/edgar/data/1562088/000162828026012246/q4fy25duolingo12-31x25shar.htmAccessed October 23, 2026
  8. [8]
    Duolingo CEO admits his controversial AI memo 'did not give enough context' and insists the company never laid off full-time employees. Fortune https://fortune.com/2025/08/18/duolingo-ceo-admits-controversial-ai-memo-did-not-give-enough-context-insists-company-never-laid-off-full-time-employeesAugust 18, 2025
  9. [9]
    Duolingo Form 10-K for fiscal year 2025. Duolingo (SEC Form 10-K) https://www.sec.gov/Archives/edgar/data/1562088/000162828026012494/duol-20251231.htmAccessed October 23, 2026
  10. [10]
    Duolingo’s battle for learning in an AI world, with Duolingo’s Luis von Ahn and Rapid Response’s Bob Safian. Masters of Scale (Rapid Response) https://mastersofscale.com/duolingos-battle-for-learning-in-an-ai-world/Accessed October 23, 2026
  11. [11]
    Backlash to Duolingo's AI memo will hit Q2 numbers, Morgan Stanley. Sherwood News https://www.sherwood.news/markets/backlash-to-duolingos-ai-memo-will-hit-q2-numbers-morgan-stanleyJuly 8, 2025
  12. [12]
    Duolingo tumbles 6% after analyst shows deceleration in active users. Sherwood News https://www.sherwood.news/markets/duolingo-tumbles-6-after-analyst-shows-deceleration-in-active-users/June 25, 2025
  13. [13]
    Duolingo Stock Fell 30% After Earnings. Here's What Investors Should Know.. The Motley Fool https://www.fool.com/investing/2025/11/06/duolingo-stock-fell-30-after-earnings-heres-what-iNovember 6, 2025
  14. [14]
    Translation app Duolingo fired some contract workers in favor of AI. Indianapolis Business Journal (The Washington Post) https://www.ibj.com/articles/translation-app-duolingo-fired-some-contract-workers-in-favor-of-aiJanuary 10, 2024
  15. [15]
    Friends don't make friends read AI-generated texts: A Duolingo Odyssey. Lars Ingebrigtsen blog https://lars.ingebrigtsen.no/2025/08/02/friends-dont-make-friends-read-ai-generated-texts-a-duolingo-odyssey/August 2, 2025
  16. [16]
    Our estimate. Hours a week of someone's time to check AI-made translations. Low is 50 hours of light checking a year divided by 52 weeks, about 1. High is 200 hours a year divided by 52 weeks, about 4. Assumptions: Same 50 hours to 200 hours a year as the checking estimate, spread evenly over 52 weeks; the volume is an assumption. Setup time is not included because no source gave one.
  17. [17]
    Our estimate. What 5 people pay freelance translators in a year for 50,000 words of Spanish and English work. Low is 50000 words at 0.08 per word, the bottom of the general Spanish rate. High is 50000 words at 0.30 per word, the top of what freelancers charge direct clients. Assumptions: The business sends out 50000 words a year; this volume is an assumption, not from a source. Rates are US market rates in USD; Mexican, Costa Rican and Panamanian freelancers may charge less, so the real figure could be lower.
  18. [18]
    Our estimate. The first year all in for the AI version: subscriptions plus paid time to check the work. Low is 200 for one Pro plan plus 50 hours of checking at 15 an hour, which is 750, for 950. High is 1500 for 5 Team seats plus 200 hours at 30 an hour, which is 6000, for 7500. Assumptions: Checking time is paid at the freelance hourly rate for general work; an owner doing it themselves pays in time, not cash. The AI version is cheaper than the freelancer version when volume and rates sit mid-range, but the high case of 7500 can exceed the low freelancer case of 4000, so savings are not guaranteed.
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Duolingo went AI-first: far more courses, slower growth | MarginWorks