Duolingo is the world's most popular language-learning platform, offering free courses in over 40 languages through a gamified, bite-sized lesson format. The app is built around short daily sessions that incorporate experience points, streak tracking, leaderboards, and interactive characters to sustain learner motivation over time. Its science-backed approach draws on spaced repetition and structured curriculum aligned with the Common European Framework of Reference for languages.

Beyond language learning, Duolingo has expanded its platform to include courses in math, music, and chess, applying the same engaging teaching method to new subject areas. The platform supports learners across all proficiency levels, from absolute beginners to intermediate students building toward conversational fluency. The Duolingo Score provides a standardized metric for learners to track and share their progress, including integration with LinkedIn.

Duolingo offers three subscription tiers: a free plan supported by advertising, Super Duolingo with an ad-free experience and unlimited hearts, and Duolingo Max which adds AI-powered features including Roleplay and Video Call with the character Lily. A Family Plan allows up to six users to share a Super Duolingo subscription. The platform is available on iOS, Android, and via web browser, with paid subscribers totaling 9.5 million as of Q4 2024.

The Duolingo English Test is a separate certified English proficiency exam accepted by over 5,500 institutions globally, including 97 of the top 100 U.S. universities. Duolingo ABC is a literacy app designed for young children. The company uses AI extensively to accelerate content creation and to power conversational learning features within the app.