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.

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

Tandem - Get fluent together. Practice languages, anytime, anywhere.

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

Fluent Forever - Learn any language using neuroscience

Yak Tack - remember. words.