Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license. Dia is roughly inspired by the commercial Windows program 'Visio,' though more geared towards informal diagrams for casual use. It can be used to draw many different kinds of diagrams. It currently has special objects to help draw entity relationship diagrams, UML diagrams, flowcharts, network diagrams, and many other diagrams.
Online Diagramming and Flowcharting Tool. Home of LibreCAD, 2D-CAD. Firefox Web Browser — Free Download. Mozilla Messaging. Chrome - The web is what you make of it.