Grammarly - Clear, effective, mistake-free writing everywhere you type.
Teachable - Create and sell beautiful online courses with the platform used by the best online entrepreneurs to sell $100m+ to over 4 million students worldwide.
Hunspell - Hunspell is the spell checker of LibreOffice, OpenOffice.
Clever - syncing between education applications for K-12 schools
DSpellCheck - Yet Another Notepad++ Spell-checking Plug-In
Claroline - Claroline is a collaborative eLearning and eWorking platform.