Features
* Easy to use Python API
* Flexible data import options
* Scalable
* Built-in reports
* Built-in data export capabilities
* Open source - easily extended
* Fast processing time (efficient use of graph algorithms)
P. Desikan, N. Pathak, J. Srivastava, and V. Kumar. ICWE '06: Proceedings of the 6th international conference on Web engineering, page 233--240. New York, NY, USA, ACM Press, (July 2006)