Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.

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.

RemNote - All-in-One Tool For Thinking & Learning

AnkiDroid - Memorize anything with AnkiDroid!

Memrise - Learn a new language with games, humorous chatbots and over 30,000 native speaker videos.

Revisy - Simplify and speed up your learning. Revisy intelligently chooses what you should revise based on your current level of understanding.