We present a Visualization, Simulation, And Graphical debugging Environment (vIsage) for distributed systems. Time-varying spatial data as well as other information from different sources can be displayed and superimposed in a single view at run-time. The main contribution of our framework is that it is not just a tool for visualizing the data, but it is a graphical interface for a simulation environment. Real world data can be recorded, played back or even synthesized. This enables testing and debugging of single components of complex distributed systems. Being the missing link between development, simulation and testing, e.g., in robotics applications, it was designed to significantly increase the efficiency of the software development process.