nauty

Nauty and Traces are programs for computing automorphism groups of graphs and digraphs. (At present, Traces does not accept digraphs.) They can also produce a canonical label. They are written in a portable subset of C, and run on a considerable number of different systems.

There is a small suite of programs called gtools included in the package. For example, geng can generate non-isomorphic graphs very quickly. There are also generators for bipartite graphs, digraphs, and multigraphs, and programs for manipulating files of graphs in a compact format.