4D - 4D is a relational database management system and IDE.
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.
ApexSQL - ApexSQL is a complete suite of tools intended for SQL servers for DBAs and developers that streamlines and automates SQL Server database management and development processes.
Clever - syncing between education applications for K-12 schools
LiveCode Platform - It is Both Under the GPL and it is also Proprietary if using the GPL version the software you make...
Claroline - Claroline is a collaborative eLearning and eWorking platform.