draw.io - Online diagramming application
Can't Unsee - A simple game to test your Design skills 🖌
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.
The Bezier Game - Beautiful game to master the Pen Tool
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Prezi Design Tool - An easy to use CANVA alternative for everyone