Grammarly - Clear, effective, mistake-free writing everywhere you type.
Mate Translate - Ultimate translation app for Mac, iOS, Chrome and many more
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
Ludwig.guru - Linguistic search engine and contextualized translator. The final solution for your writing doubts!
Editsaurus - Highlights potential pitfalls in your writing to encourage good habits.
Lingvanex - Translation apps for business, travels, professional translators, students and free style people.