Gephi

Gephi is the leading visualization and exploration software for all kinds of graphs and networks. Gephi is open-source and free. Gephi is an award-winning open-source platform for visualizing and manipulating large graphs. It runs on Windows, Mac OS X and Linux. Localization is available in English, French, Spanish, Japanese, Russian, Brazilian Portuguese, Chinese, Czech and German. Fast Powered by a built-in OpenGL engine, Gephi is able to push the envelope with very large networks. Visualize networks up to a million elements. All actions (e.g. layout, filter, drag) run in real-time. Simple Easy to install and get started. An UI that is centered around the visualization. Like Photoshop™ for graphs. Modular Extend Gephi with plug-ins. The architecture is built on top of Apache Netbeans Platform and can be extended or reused easily through well-written APIs.