Setting up a drone swarm generally requires coordinating hardware and software to act as a unified entity.
While there is no single software titled "Drone Swarm" that is widely available for free download as a consumer application, you can download several free open-source frameworks and simulators to design, simulate, and control your own drone swarms. Free Open-Source Swarm Software
: You will typically need one radio telemetry module per drone to connect them to a central Ground Control Station (GCS).
: This platform is designed specifically for drone light shows and swarm management. It allows you to design sky shapes and export them for use with flight controllers.
: A comprehensive ground control station that includes built-in swarming features. You can access the Swarm interface by pressing Control+F while connected to a "leader" vehicle to set offsets and connect multiple MAVs.
If you are looking for tools to build or simulate a swarm, these industry-standard platforms are available for free: