Here’s a collection of website that host graph datasets that can be used for research and development purposes
Big Graph Data Set: Includes links to general graphs, RDF Graphs and Synthetic Graph generators.
Konect: Include links to unidirectional, bidirectional and bipartite graphs with up to 2.5 billion edges.
Stanford Large Network Dataset Collection: Includes social network graphs, citation graphs, web graphs, collaboration networks and other types of graphs.
If you know other graph dataset repositories that I haven’t mentioned. Let me know.