LeitnerBox VS WordsKeeper

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.

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

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

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.

Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.

Flashcard Hero - Mac flashcard study app that saves you time memorizing information by keeping track of what you already know so you can focus on what you don't know.