If you are looking for a tool like Visio for creating diagrams but don’t want to spend any money, well…there is an alternative. Dia is a great tool for creating diagrams like UML, flowcharts or entity relationships. It is developed with GTK+ and is supported on Windows, Linux and Unix. Check out this website for more details and to download the installer for Windows.
UML diagram example
Tool palette window
Posted by Deviloper 