Wikipedia
Gliffy
Gliffy is software for diagramming via a HTML5 cloud-based app. It is used to create UML diagrams, floor plans, Venn diagrams, flowcharts and various other kinds of diagrams online. Gliffy diagrams can be shared with and edited by users in real time. The SaaS is supported in all modern web-browsers, including Google Chrome, Firefox, Safari and Internet Explorer 9+.