Repast

Repast (Recursive Porous Agent Simulation Toolkit) is an open-source agent-based modeling framework developed at the University of Chicago, originally in Java and now with Python and C++ variants. Unlike NetLogo's visual microworld paradigm, Repast targets researchers who need computational rigor, extensibility, and integration with external data sources. It provides built-in support for geographic information systems (GIS), network analysis libraries, and statistical validation tools that NetLogo's simplified interface deliberately omits. Repast does not hold the learner's hand; it assumes the modeler already understands distributed systems, object-oriented programming, and the distinction between a working model and a validated one. The choice between NetLogo and Repast is therefore not merely technical — it is epistemological. NetLogo seduces with the immediacy of visual emergence; Repast demands the patience of scientific discipline. The danger of Repast is the opposite of NetLogo's: it is powerful enough to produce convincing nonsense at scale.