CMU alumnus Luis von Ahn gamified language learning and revolutionized an industry
Luis von Ahn didn’t set out to change how people around the world, from refugee camps to C-suites, learn a new language — but he and his ubiquitous green owl did exactly that.
A CMU alumnus and former faculty member, von Ahn co-founded the language learning app Duolingo, where he serves as CEO and a board member of the Pittsburgh-based company. He returned to campus during CMU125 at Homecoming Weekend as the featured speaker for the President’s Lecture Series: CMU125 Kick Off to share the story of Duolingo and how CMU influenced his life and career.
“I think learning is good and useful and good for humanity,” says von Ahn. “I think it’s the best thing I can do for the world.”
Origin story
As the only child of a single mother in Guatemala, von Ahn saw firsthand the stark inequalities in educational opportunities in his home country, a place where the wealthy could afford the best education while others barely learned to read and write.
“A lot of people talk about education as something that brings equality to different social classes,” von Ahn says. “What I saw as a child was the opposite.”
When he was 8, he asked for a Nintendo for his birthday. He received a Commodore 64 computer instead. By age 10, von Ahn was creating his own computer games and in love with math and computer science.
In 2000, he graduated summa cum laude from Duke University with a bachelor’s degree in mathematics. He chose to attend Carnegie Mellon for his Ph.D., charmed by University Professor Manuel Blum during his first visit to campus.
“[CMU] is where I really learned how to think like a computer scientist,” Ahn says. “It just changes the way you think — even your vocabulary starts being different.”
He credits Blum for helping him learn how to think deeply, including a months-long exercise where Blum feigned misunderstanding until von Ahn could describe the concept from a research paper in simple terms in just a few minutes.
“I could only give him that explanation, that very deep explanation, after three months of really trying to explain it to him,” von Ahn remembers.
His doctoral thesis, “Human Computation,” explored methods of combining human brainpower with computers to solve problems that neither could tackle alone. This theme comes up again and again throughout von Ahn’s subsequent research and entrepreneurial ventures.
Millions of times a day, people type in distorted letters or identify all the bicycles in a grid to verify they’re human online. They can thank von Ahn for that. He developed the CAPTCHA verification system with Blum, who was also his Ph.D. adviser. And later, as a faculty member, he sold reCAPTCHA, a refined version, to Google.
In 2011, he was advising a CMU Ph.D. student, Severin Hacker. Both von Ahn and Hacker were non-native English speakers — von Ahn’s first language was Spanish while Hacker’s was Swiss German. From personal experience, both recognized the immense personal and economic value of learning English for people all over the world. In their quest to find a project to work on together, their shared appreciation for the power of language seemed like a natural starting point. And Duolingo was born.
Make it fun
“It turns out that your average person doesn’t really, even if they say so, want to learn stuff,” says von Ahn. “We have to make it fun for them to actually want to do it.”
Their initial versions of the program didn’t inspire engagement — even for the two creators, who began the project by learning each other’s languages. They realized they had to make it more entertaining to motivate people to keep coming back.
“Make it fun” is one of the core operating principles of Duolingo, and that refers to both the product they produce and the work culture they foster in the company’s Pittsburgh-based headquarters and offices in New York, Seattle, Detroit, Berlin and Beijing. (Read more about Duolingo’s culture in the Alumni Community.)
Duolingo was built to feel like a game with users engaged in friendly competitions on leaderboards, maintaining their streaks, earning points, and unlocking achievements and virtual currency. Lessons in reading, writing, listening and speaking are compact and easily completed in minutes.
Looking beyond the fun characters and prizes, Duolingo has used AI, along with the world’s largest data pool on language learning, to provide personalized, adaptive lessons. They’re one of the first companies to effectively monetize AI with their “Video Call with Lucy” premium feature, which allows users to practice speaking skills in a low-pressure way.
“The way we think about AI is as an accelerant for our effort, not as a replacement for humans,” says von Ahn.
Since 2012, Duolingo has been the most downloaded education app in App Store history. With over 100 million regular users each month, more people are learning a second language using the app than in the entire U.S. public school system.
Funding the mission
After a few years of growth, von Ahn and the company had to answer a hard question: Can doing good for the world also be good for business?
He and the company remained committed to their mission of universally available education. All learning content on the app remains free. Those using the app for free are shown ads upon finishing a lesson. Premium subscriptions remove ads and offer additional features, like the “Video Call with Lucy” option.
This “freemium” model equates to a small percentage of paying subscribers effectively subsidizing a free education for the vast majority of the company’s users. Duolingo is now profitable, valued at $9 billion, and has become the model for successfully using technology to provide a desperately needed educational tool to those who can least afford it.
“On one side, you have refugees whose net worth is essentially zero. On the other side, you have somebody whose net worth is like $100 billion. And they’re both using the same system,” says von Ahn.
The company went public in 2021 and in 2024 made nearly $750 million in revenue. Today, they offer 248 total language courses for more than 40 distinct languages and have also branched into teaching math, music and chess.
The company's focus on teaching math is von Ahn's self-professed passion project.
“I’m not a language nerd. I love what we’re doing, but what I love to learn is math,” von Ahn says.
Even though math is a universal language — and often a challenging subject for learners — von Ahn isn't lowering his expectations.
“The Pope uses Duolingo to learn languages. I would like to see him use it to learn math!”