The Open Graph Viz Platform

Gephi is the leading visualization and exploration software for all
kinds of graphs and networks. Gephi is open-source and free.

Exploratory Data Analysis: intuition-oriented analysis by networks
manipulations in real time.

Link Analysis: revealing the underlying structures of associations
between objects.

Social Network Analysis: easy creation of social data connectors to
map community organizations and small-world networks.

Biological Network analysis: representing patterns of biological data.

Poster creation: scientific work promotion with hi-quality printable
maps.

METRICS READY

Centrality: used in sociology to indicate how well a node is
connected. Available: degree (power-law), betweenness, closeness.

And more: density, path length, diameter, HITS, modularity, clustering
coefficient.

TECHNOLOGY

Ergonomic interface: no programming skills needed

High-performance: built-in rendering engine.

Native file formats: GDF (GUESS), GraphML (NodeXL), GML, NET (Pajek),
GEXF and more.

Customizable by plugins: layouts, metrics, data sources, manipulation
tools, rendering presets and more.

NOTE: Gephi's support for importing even non-trivial Graphviz dot is
totally broken, so do not rely on it. For dot, the graphviz package
is providing the gvedit tool.