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.

draw.io - Online diagramming application

yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.

textografo - Online diagramming application which generate diagrams based on text and allows real time...

Excalidraw - Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.

Arcentry - Create interactive cloud diagrams. Arcentry helps you visualize the full picture of your infrastucture - in realtime and at any scale.