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.
Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Treehouse - Treehouse is an award-winning online platform that teaches people how to code.
Textpattern - Textpattern is an elegant content management system that is free, open source software.
PowerSchool - PowerSchool provides a K-12 education technology platform for operations, classroom, student growth, and family engagement.
TYPO3 - TYPO3.com - Infos, SLAs, Extended Support Versions and more