Résumé : We present MoCA: an open-source modular system to perform experiments with robot swarms. Robot swarms are self-organized and highly redundant groups of robots that act collectively to achieve a shared goal. The collective behavior of a robot swarm emerges from the interaction that individual robots have with their peers, and with objects in the scenario where they operate. MoCA provides tools to create, simulate, and physically deploy scenarios where robots react to the color displayed by programmable RGB modules. Users of MoCA can create these scenarios—also known as robot arenas—by assembling the RGB modules in polygonal structures that enclose the workspace of the robots. We describe the hardware and software architecture of MoCA, and we point to the repositories that have the resources to build and operate the system; as well as a plug-in to simulate the system in ARGoS3. MoCA has been used to conceive scenarios and missions in two swarm robotics studies: (i) swarms of e-puck robots that operate with control software produced via optimization; and (ii) swarms of e-puck robots that coordinate using indirect communication. The robot platform we target is the e-puck robot and the implementation of MoCA we present here is made to work with this robot.