See the Call Graph Drawing Interface page for more information. Graph Drawing Tools daVinci is a graph layout tool written in the functional language ASpecT, with a C interface. It is similar to the VCG tool but has more features to communicate with controlling programs acting as a user interface for these programs. See the daVinci home page for more information. GraphEd is a graph editor with a large number of algorithms concerning graphs, including automatical layout, many forms of partitionings, planarity tests etc.
Libraries are also available.
See the GraphEd home page for more information. It provides GraphScript, a scripting language to support user interface and animation tailoring of the graph editor. Is is also the first tool that uses GML for input and output. GML is an upcoming standard for graph specifications. See the GraphLet home page for more information.