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.
Mondly - Learn 33 languages in 500 bite-size lessons and 14 conversational modules.
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.
Yak Tack - remember. words.