UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.

System Designer - System Designer is a low code development platform that you can use to create UML-based models.

Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.

WhiteStarUML - WhiteStarUML is a fork of StarUML with an intent to revive its Delphi code base by updating code to...

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.

Dynamic Draw - A Powerful idea processor.It's Open Source and Freeware.