Hunspell - Hunspell is the spell checker of LibreOffice, OpenOffice.
GNU Aspell - GNU Aspell, usually called just Aspell, is a free software spell checker designed to replace Ispell.
Enchant - The easiest way to scale personalized customer support
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.
Grammarly - Clear, effective, mistake-free writing everywhere you type.
tinySpell - A spell-checker for Windows. Checks text in clipboard and/or on the fly in any Windows program. Small and easy to use. Resides in the taskbar notification area. Free download.