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

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.

Synonymful - Improve your vocabulary and communicate like a pro.

Yak Tack - remember. words.

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.