Inside Duolingo Unhinged Growth to a $500M Business

Kansu describes the lesson as Duolingo’s core loop, supported by streaks, daily quests, and celebrations. The goal is to make learning feel enjoyable because books can teach effectively but are difficult to stick with. Streaks and weekly leaderboards encourage learners to return and complete more lessons.

Duolingo uses character-driven push notifications, including reminders voiced by Duo, and improves their copy, timing, and personalization. Kansu also points to continually improving course content and placing learners at the right level as growth contributors. The company embraces an “unhinged” brand style, from unusual app icons to local TikTok accounts, to build character and brand affinity.

When Kansu joined in 2016, Duolingo had users but no revenue. The company tested ads, in-app purchases, and subscriptions while keeping lessons free; paying and nonpaying users can learn the same material. Subscriptions eventually grew to more than 80% of revenue through repeated experiments with features, promotion, and purchase flows.

Duolingo uses generative AI to speed up course content creation, though Kansu says it cannot yet generate a whole course at the press of a button. Its Video Call feature lets learners practice speaking with Lily, whose vocabulary and pace adapt to their level. The team tests features internally, then through small A/B rollouts, while using guardrails and iterating on the experience.

Kansu says metrics alone can lead teams to spam users or create poor experiences, so Duolingo uses leadership product reviews and a “Take the Long View” principle. He advises product managers to develop an eye for design, seek work with clear business impact, and learn through frequent hands-on experiments. He also emphasizes shipping useful products over relying on strategy documents or stakeholder alignment as accomplishments.