Visustin - Visustin is a flowchart generator to make you able to visualize your source code UML activity diagrams and flowcharts.
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
SmartDraw - Instead of starting with a blank screen, SmartDraw gives you the exact template you need.
draw.io - Online diagramming application
Grapholite - Powerful Windows 10, iPad, Android and Desktop solution for the creation of flowcharts, org charts, floor plans, uml diagrams, bpmn diagrams, mind maps, venn charts, web site structures and wireframes, network layouts etc.
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.