Luis von Ahn

To apply to college in the United States, Luis von Ahn had to fly from Guatemala to El Salvador and pay more than $1,200 to sit an English exam. Duolingo gives away the language course and sells the test.¹

Von Ahn is the co-founder and chief executive of Duolingo, a free, gamified language-learning app that also offers courses in math, music, and chess and monetizes through a premium subscription and a standardized English proficiency exam. Duolingo trades publicly on Nasdaq under the ticker DUOL and reached roughly 130 million monthly active users by early 2025. Before Duolingo, von Ahn was an academic computer scientist known for inventing CAPTCHA and reCAPTCHA.

Background

Von Ahn was born on August 19, 1978, in Guatemala City, Guatemala. He was raised by his mother, one of the first women in Guatemala to complete medical school, who worked as a single parent and directed most of the family's resources toward his education. He grew up around a family candy factory and has recalled taking apart its machines around age 11. He also recalls expecting a Nintendo as a child and instead receiving a Commodore 64: "I was pretty upset. I guess it changed my life."²

Guatemala's civil war shaped his early years; his aunt was kidnapped in 1995, which he says hardened his determination to study abroad.² To apply to United States colleges he had to fly to El Salvador and pay more than $1,200 to sit the TOEFL exam, an experience he frequently cites as the origin of a lasting grievance against standardized-testing systems he views as extractive.

Von Ahn earned a degree in mathematics from Duke University in 2000, graduating summa cum laude, then a PhD in computer science from Carnegie Mellon University in 2005, advised by Turing Award winner Manuel Blum. His dissertation contained the first published use of the term "human computation."

Getting started

In 2000, as a graduate student, von Ahn helped invent CAPTCHA with Manuel Blum, Nicholas Hopper, and John Langford, after Yahoo sought a way to stop automated bots. He gave the solution to Yahoo for free: "I was an academic trying to get a PhD. It just hadn't occurred to me." He calculated that roughly 200 million CAPTCHAs solved daily at about ten seconds each amounted to some 500,000 human-hours per day, and the sense of waste this produced became the seed of his research agenda around harnessing distributed human effort that computers could not replicate.³

He built the ESP Game, a crowdsourced image-labeling game that Google licensed in 2006 as Google Image Labeler. In 2006, at age 27, he became a MacArthur Fellow, the youngest recipient in his cohort year. In 2007 he invented reCAPTCHA, which repurposed the act of solving CAPTCHAs to digitize old books and newspapers whose text optical character recognition could not read, including New York Times archives dating back to 1851. Google acquired reCAPTCHA in 2009.

After a brief pause, von Ahn partnered with Severin Hacker, a Carnegie Mellon PhD student from Switzerland. Both were non-native English speakers who saw English fluency as a major economic lever, and they set out to build free language education technology.

What he built

The company that became Duolingo is headquartered in Pittsburgh, Pennsylvania, with Hacker as co-founder and chief technology officer. A private beta launched in November 2011 with a waiting list reported at 300,000 people, followed by a public launch in June 2012.³ The company raised successive venture rounds from Union Square Ventures, New Enterprise Associates, Kleiner Perkins, Google Capital, Drive Capital, and Alphabet's CapitalG, reaching a $1.5 billion valuation in a 2019 round. Duolingo went public on Nasdaq on June 28, 2021.

By 2024 the company reported revenue of roughly $748 million and net profit of about $88.6 million, with around 830 employees.² It counted about 10.9 million paying subscribers by mid-2025. Beyond its core courses, Duolingo built the Duolingo English Test, a significant revenue line; Duolingo Max, an AI-powered conversation and roleplay tier introduced in March 2023; math and music courses in October 2023; a chess course in April 2025; and a large expansion of AI-generated courses. Von Ahn also joined Figma's board of directors in July 2025.

How he operates

Von Ahn describes a recurring pattern across his work: turning what looks like waste, whether idle human attention, user friction, or avoidance of hard tasks, into something productive, the same logic that runs from CAPTCHA to reCAPTCHA to Duolingo's gamification. He believes gamification is what makes practice sustainable, saying the company has tried to make "the broccoli taste like dessert." He treats the free tier as the mission rather than a funnel, with premium subscribers subsidizing free users, an approach he casts as an inversion of the typical paywall-first edtech model. He has said it is rare to see the same product used by billionaires and refugees, and that within Duolingo more money cannot buy a better education.¹ He also frames education as something that can divide rather than equalize, since the wealthy can buy strong schooling that helps them stay wealthy. Von Ahn has said his central drive is simply to have an impact, and he treats founder anger at extractive institutions as legitimate, durable product fuel.

Where things stand

As of 2025 von Ahn continues to serve as chief executive of a profitable, publicly traded company with continued growth in users and subscribers and an aggressive push into AI-driven course generation alongside chess, math, and music. He received the 2018 Lemelson-MIT Prize. He sits on Figma's board of directors.

Key facts

• Co-invented CAPTCHA at Carnegie Mellon in 2000 and gave it to Yahoo for free.
• Invented reCAPTCHA in 2007, which helped digitize archival newspapers and books; Google acquired it in 2009.
• Became a MacArthur Fellow in 2006 at age 27, the youngest in his cohort year.
• Co-founded Duolingo with Severin Hacker; private beta launched November 2011, public launch June 2012.
• Took Duolingo public on Nasdaq in June 2021; the company reported about $748 million in 2024 revenue.
• Cites paying more than $1,200 and flying abroad to take the TOEFL as a founding motivation for free education.