PolyglotTrainer is described as 'Vocabulary trainer for polyglots: people who speak and want to maintain 4+ languages. Very simple and focussed on one goal: to learn the 1000 most common words of several languages in parallel' and is a language learning tool in the education & reference category. There are more than 10 alternatives to PolyglotTrainer, not only websites but also apps for a variety of platforms, including iPhone, Android, iPad and Android Tablet apps. The best PolyglotTrainer alternative is AnkiDroid, which is both free and Open Source. Other great sites and apps similar to PolyglotTrainer are Duolingo, LibreLingo, Memrise and Rosetta Stone.