OverSim is an open-source overlay and and peer-to-peer network simulation framework for the OMNeT++ simulation environment. The simulator contains several models for structured (e.g. Chord, Kademlia, Pastry) and unstructured (e.g. GIA) peer-to-peer protocols.

OverSim was developed at the Institute of Telematics, Universität Karlsruhe (TH) within the scope of the ScaleNet project funded by the German Federal Ministry of Education and Research.