Diashapes is a small tool that makes it easy to download and install additional Dia symbols.
Dia is an open source general-purpose diagramming software, inspired by the commercial Windows program "Visio", though more geared towards informal diagrams for casual use. Dia 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.

Diashapes Features:
1. Draw structured diagrams
2. Many predefined objects and symbols
3. cross-platform

The license of this software is Free, you can free download and free use this flowchart & diagram software.