gephi - Open Graph Viz Platform
Gephi is an interactive visualization and exploration platform for all kinds of networks and complex systems, dynamic and hierarchical graphs. Gephi is a tool for people that have to explore and understand graphs. It helps data analysts to make hypothesis, intuitively discover patterns, isolate structure singularities or faults during data sourcing.
It supports Real-time visualization, Dynamic Network Analysis, Metrics, Cartography, Clustering and hierarchical graphs etc. It is modular based design and therefore allows developers to add and extend functionalities.