An IoT platform's job is to take telemetry from a huge, unruly fleet of devices and turn it into something applications can consume — and at the center of that job sits a message broker. This simulator visualizes that hub-and-spoke architecture directly: devices on the inner ring publish messages toward a central broker, which queues them and drains that queue at a fixed processing throughput, fanning each delivered message out to subscribers on the outer ring. Push the device count or publish rate past what the broker's throughput can absorb and the queue tower keeps climbing — the same saturation point that drives real platform capacity planning, partitioning and autoscaling decisions.