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.

Eduflow - Digital learning that actually teaches students something

Editsaurus - Highlights potential pitfalls in your writing to encourage good habits.

Backchannel Chat - Backchannel Chat is best in class discussion tool that is intended for teachers to streamline their class activities.