Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

Zorbi - Spaced-Repetition Flashcards - Other tools are built by boomers, Zorbi is built by students.

Lingvist - Lingvist helps you take your foreign language skills to the next level with a broad selection of exercises and lessons.

SmartCards+ - Spaced Repetition Software for iOS. Modern, powerful and easy to use.

Fluent - Fluent is a people-based marketing platform that uses real-time, one-to-one interaction to create custom audiences and serve personalized ads that drive performance at scale.

Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.