LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
StoryMill - Developers and publishers of Mac, Win, and iOS productivity, home and office and writing software such as MacGourmet, Paperless and many more. Based in MN.
Grammarly - Clear, effective, mistake-free writing everywhere you type.
BlankPage - Stay motivated to write, and finish your story
Druide Antidote - Que vous rédigiez une lettre ou un courriel, cliquez sur un bouton et voyez s’ouvrir un des ouvrages de référence parmi les plus riches et les plus utiles jamais produits.
Manuskript - Open-source tool for writers.