We propose a simulation tool able to test hybrid GNSSterrestrial and cooperative positioning algorithms that fuse both pseudorange measurements from satellites and range estimates between terrestrial receivers. In particular, the tool simulates devices belonging to a peer-to-peer (P2P) network where peers cooperate by exchanging data in order to improve both positioning accuracy and availability.More specifically, the simulation tool generates range and pseudorange measurements by employing realistic propagation models and GPS orbits. Furthermore, the simulation tool allows the user to test different algorithms based on Bayesian and least squares methods in two realistic GNSS challenged scenarios namely indoor and urban canyon. Finally, the simulator take into account communication and mobility aspects allowing the user to evaluate their impact on the final positioning accuracy.