Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
System Designer - System Designer is a low code development platform that you can use to create UML-based models.
LaTeXDraw - LaTeXDraw is a graphical drawing editor for LaTeX.
WhiteStarUML - WhiteStarUML is a fork of StarUML with an intent to revive its Delphi code base by updating code to...
Ipe - Ipe is a drawing editor for creating figures in PDF or (encapsulated) Postscript format.
Dynamic Draw - A Powerful idea processor.It's Open Source and Freeware.