Duolingo, Inc., is an American educational technology company that produces learning apps and provides language certification. Duolingo offers courses on music, math, and 43 languages, ranging from English, French, and Spanish to less commonly studied languages such as Welsh, Irish, and Navajo, and even fictional languages such as Klingon. The learning method incorporates gamification to motivate users with points and rewards and interactive lessons featuring spaced repetition. The app promotes short, daily lessons for consistent-phased practice.
https://en.wikipedia.org/wiki/Duolingo