KeepYourHead is a latex based flashcard trainer under GPL3. It includes an editor as well as an trainer. Flashcards are build in latex. Latex is a powerful tool for descriping documents. The Flashcards are checked by letting the user judge if he knew the answer well enough.
Gemfile gem 'keepyourhead', '~> 0.2.1'
install gem install keepyourhead -v 0.2.1