Diagram Maker | Online Diagram Software | Creately
From the information on the website.
"Realtime Diagram Collaboration"- work with 2 or 20 from anywhere in the world. Shared projects, secure publishing and more
"Diagramming and Collaboration" - Beautiful, easy and built for teams. Flowcharts, UML, UI mockups and more.
"Diagramming on your Desktop: - Full-featured desktop app; work fully offline or collaborate online.
"Beautiful diagrams in no time" - Choose from 1000 ready-made templates; extensive shape libraries and 100,000 examples."
No registration is required to use the first time.
Be sure and check out the "customer love"page: https://creately.com/Customer-Love