In this paper, we present the most important features of SeSAm, a modeling and simulation platform for multi-agent simulations. Based on a declarative, explicit model representation and visual programming, it allows implementing models on specification level. Optimizing compilation allows efficient simulation of the explicit model representation. It was successfully applied in different areas, like biology, traffic or logistics simulation. Categories and Subject Descriptors I.6.7 [Simulation and Modeling]: Simulation Support Systems Environments General Terms Design, Experimentation, Languages Keywords Agent-based Simulation, Visual Programming