Cosmos is a statistical model checker for Hybrid Automata Stochastic Logic (HASL). HASL uses Linear Hybrid Automata (LHA), a generalization of Deterministic Timed Automata (DTA), to describe accepting execution paths of a Discrete Event Stochastic Process (DESP), a class of stochastic models which includes, but is not limited to, Markov chains. As a result, HASL verification turns out to be a unifying framework where sophisticated temporal reasoning is naturally blended with elaborate reward-based analysis. Cosmos takes as input a DESP (described in terms of a Generalized Stochastic Petri Net (GSPN)), a LHA and an expression Z representing the quantity to be estimated. It returns a confidence interval estimation of Z. Cosmos is written in C++ and is freely available to the research community. It is jointly developed by researchers of the Institute National de Recherche en Informatique et Automatque (INRIA) and of the Laboratoire Algorithmique Complexit´e et Logique ( LACL) of the Universit´e Paris-Est Cr´eteil. Since its introduction [8] the tool has evolved with the addition of a number of new features including support for rare-events systems and for hybrid systems.