WhiteStarUML - WhiteStarUML is a fork of StarUML with an intent to revive its Delphi code base by updating code to...
draw.io - Online diagramming application
Topcoder - The Topcoder home page has received a slick new makeover that lets new customers quckly login, discover the power of our community, and launch challenges.
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
UModel - UModel is a web-based tool that enables developers to use UML diagrams to express their software requirements.
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.