LingQ is described as 'Immerse in language learning using authentic audio, text, and online content, track vocabulary progress, review with SRS, and study offline or online' and is a language learning tool in the education & reference category. There are more than 50 alternatives to LingQ for a variety of platforms, including Web-based, iPhone, Android, iPad and Google Chrome apps. The best LingQ alternative is Duolingo, which is free. Other great apps like LingQ are Little Language Lessons, LingoUnify, TextStack and Lexi Explorer.
It actually supports EPUBs