Grammarly - Clear, effective, mistake-free writing everywhere you type.
GradeProof - Proofreading with Artificial Intelligence
GrammarChecker.net - Grammar Checker is an online spell check tool. It effectively works on English sentence correction, Punctuation mistakes of 28 other different languages.
Grammatica - AI powered writing assistant
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
EditMyPaper.ca - Fast and accurate English editing for essays, general papers, research papers and manuscripts.