igraph

igraph is a library collection for creating and manipulating graphs and analyzing networks.

[3] The software is widely used in academic research in network science and related fields.

[4] It is written in the C programming language in order to achieve good performance and it is freely available under GNU General Public License Version 2.

The C library and R and Python packages need the respective software, otherwise igraph is portable.

igraph can read and write file formats such as Pajek, GraphML, LGL, NCOL, DIMACS, and GML, as well as simple edge lists.

An example of a graph created using igraph, representing the email network of the Enron Corpus