EduDo - EduDo is a video discussion platform
draw.io - Online diagramming application
Courseroot - Biggest online course database on the web
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
TeenUp - A learning platform designed for teens by teens
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.