Luis von Ahn: the genius who transformed small clicks into the greatest investment in modern education.
Before Duolingo, there was a problem:
Bots were breaking the internet.
A graduate student transformed this pain point into his first billion-dollar idea.
Luis von Ahn helped invent CAPTCHA at Carnegie Mellon.
Those garbled little words filtered bots from humans, on a planetary scale.
Then came reCAPTCHA:
Same task, new purpose—decoding ancient books with human touches.
In 2009, Google acquired the technology.
Luis learned the lesson:
Small actions, repeated millions of times, change the world.
He grew up in Guatemala, seeing gifted children out of school.
The mission became crystallized: to make high-quality education free for everyone.
- Duolingo is born in Pittsburgh. A learning app disguised as a game. Free. Fun. Scientifically rigorous. The growth engine? Behavioral design with ethics. Streaks, XP, rankings, friendly rivalry. Relentless A/B testing: every button, sound, and screen is measured. If a variant improves retention by 0.2%, it's released. The first revenue models failed. Duolingo adjusted: Ads for free users Subscriptions for advanced users English proficiency test. AI became the teacher's assistant. Personalized paths, instant feedback, intelligent review. The "explain my answer" is a tutor in your pocket. The brand became a fortress. The little green owl turned notifications into memes. 130 million people learning languages on their phones. Behind it: a data flywheel that gets sharper with each exercise. More learners → better models → better lessons → more learners. What looks like a game is a system of clear feedback, quick rewards, visible progress.
Education designed to generate daily momentum.
From "prove you're human" to "unlock your future."
An $8 billion company, driven by people who couldn't afford school.
Now teaching the next generation to overcome that fate.