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.
Grammarian PRO3 - Grammarian PRO3 is a feature-rich grammar checker that enables you to write better content without taking assistance from the English teacher.
Eduflow - Digital learning that actually teaches students something
Gramlee.com - Online grammar check, proofreading and copy editing services.
Kialo - Kialo is the platform for rational debate. Empowering reason through friendly and open discussions.
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.