Anki is a spaced repetition flashcard program. 

OpenTeacher is a quality teaching software which you can also use to learn or improve your English language easily.
OpenTeacher is an opensource application that helps you learn a variety of subjects.

You just enter the questions and the answers, or download them from the internet, and OpenTeacher tests you.

OpenTeacher has the following features:

English Today Lite is a free program that allows you to improve your English pronunciation, reading and listening skills. 

English Today Lite is designed to help you improve your English skills by working with various tools and taking tests to evaluate your progress. It comes with a variety of exercises that can enhance your language speaking and pronunciation abilities.
Interactive learning tools and interesting puzzles.

Memrise is an innovative way to learn English words online for free.
Memrise has designed a scientific method of learning that’s as simple and intuitive as possible, but above all, Memrise makes learning as fast as possible. Memrise breaks what you have to learn into little chunks; it helps you form clear memories, and it makes sure you never forget what you learn, with adaptively timed reminders and tests.

Duolingo is a free language-learning and crowdsourced text translation platform.
It is available on the Web, iOS, Android and Windows Phone 8.1 platforms.
Duolingo provides extensive written lessons and dictation, with speaking practice for more advanced users. It has a gamified skill tree that users can progress through and a vocabulary section where learned words can be practiced.

Byki Express - is a free language-learning software.

Many other language learning programs start by teaching grammar. Byki Language Learning Software is different. It leverages the fact that adults learn foreign languages by collecting words and phrases in their memory, like items in a basket; that vocabulary is more fundamental than grammar.

StudyBlue is a collaborative learning ecosystem that empowers more than 7 million people to master any subject. Students can connect with others who are on a similar learning journey through a shared library of more than 250+ million pieces of user-generated content. StudyBlue brings together the wisdom of the crowd.