SuperMemo is described as '(from "Super Memory") is a learning method and software package developed by SuperMemo World in Poland from 1985 to the present. It is a practical application of the spaced repetition learning technique that has been proposed for efficient instruction by a' and is a language learning tool in the education & reference category. There are more than 50 alternatives to SuperMemo for a variety of platforms, including Web-based, Android, iPhone, iPad and Windows apps. The best SuperMemo alternative is Anki, which is both free and Open Source. Other great apps like SuperMemo are AnkiDroid, RemNote, Memrise and Mochi.
Anki is under active development, and has a large user community. There are many videos on YouTube showing how to use it, and giving tips.