Netzschleuder

Online catalogue and repository of over 160K network datasets with the aim of aiding scientific research. The website is meant to be browsed both by humans and machines alike, and can also be accessed via a convenient JSON API, or via the graph-tool library. The network datasets themselves are available in several machine-readable formats, in particular gt, GraphML, GML and CSV. 

Available at: https://networks.skewed.de