yEd Graph Editor

yEd is a powerful desktop application that can be used to quickly and effectively generate high-quality diagrams. Create diagrams manually, or import your external data for analysis. yEd is freely available and runs on all major platforms. yEd is a pure Java Swing application. It runs on all Windows, Unix/Linux, and Mac OS versions where a suitable Java Runtime Environment is available. yED Graph editor is one of the most loved free Microsoft Visio alternative.