LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.

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.

Grammarly - Clear, effective, mistake-free writing everywhere you type.

Fluent - Fluent is a people-based marketing platform that uses real-time, one-to-one interaction to create custom audiences and serve personalized ads that drive performance at scale.

Gramlee.com - Online grammar check, proofreading and copy editing services.

Lingvo TV - Learn languages while watching movies on Netflix.