Abstract. CaVi provides a uniform interface to state-of-the-art simulation methods and formal verification methods for wireless sensor network. Simulation is suitable to examine the behavior of a wireless sensor network in great detail. Due to the probabilistic behavior of these systems, however, the simulation covers only a small fraction of all possible behaviors. Formal model checking techniques, based on Markov Decision Processes, use less detailed and more abstract models and compute exact probabilities and expected values for the entire behavior, where simulation can only give averages. CaVi allows for creating a single model for simulation, Monte-Carlo simulation, and model checking.