Simulation is becoming increasingly important in the analysis and design of complex systems with natural and artificial components. CD++ is a modeling and simulation tool that was created to study these kinds of systems by using a discrete event cell-based approach. It was successfully employed to define a variety of models for complex applications. Here, the authors present different extensions done to the tool using a client-server architecture. Users can create models in local workstations, execute them in a remote high-performance simulation engine, and then receive, visualize, and analyze the results locally with easy-to-use 2D and 3D interfaces. The 3D interface was built using the virtual reality markup language (VRML) to facilitate Web-based visualization. The tool now enables running several models simultaneously and supports multiview outputs.