Wikipedia
Sparksee (formerly known as DEX) is a high-performance and scalable graph database management system written in C++.
Its development started in 2006 and its first version was available on Q3 - 2008. The fourth version is available since Q3-2010. There's a free community version, for academic or evaluation purposes, available to download (link web) limited to 1 Million nodes, no limit on edges.
Sparksee is a product originated by the research carried out at DAMA-UPC (Data Management group at the Polytechnic University of Catalonia). On March 2010 a spin-off called Sparsity-Technologies has been created at the UPC to commercialize and give services to the technologies developed at DAMA-UPC.
DEX changed name to Sparksee on its 5th release on February 2014.