Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

Power Thesaurus - Power Thesaurus is a fast, comprehensive and easy-to-follow online thesaurus for writers...

Mondly - Learn 33 languages in 500 bite-size lessons and 14 conversational modules.

WordWeb - One-click lookup in any almost any Windows program; Hundreds of thousands of definitions and synonyms; The latest international English words; Works offline, or reference to Wikipedia and web references.

MondlyAR - Learn languages in augmented reality

Artha - Artha is a handy thesaurus based on WordNet with distinct features like global hotkey look-up...