NetworkX

NetworkX is a Python library for studying graphs and networks. NetworkX is free software released under the BSD-new license.
Suitability.
NetworkX is suitable for operation on large real-world graphs: e.g., graphs in excess of 10 million nodes and 100 million edges. Due to its dependence on a pure-Python "dictionary of dictionary" data structure, NetworkX is a reasonably efficient, very scalable, highly portable framework for network and social network analysis.
Integration.
NetworkX is integrated into SageMath.