Grammarly - Clear, effective, mistake-free writing everywhere you type.
SSuite Spell Checker - SSuite Office's free spell checker provides you with a handy means of checking the spelling in order to make sure your words are correctly typed or written.
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
Ginger - Powerful and effortless desktop & mobile solutions for improving your writing and productivity. Ginger Software is your personalized editor - everywhere you go.
Hunspell - Hunspell is the spell checker of LibreOffice, OpenOffice.
ClipMem 3 - Advanced Clipboard-Manager