VerneMQ is an open-source, high-performance, distributed MQTT broker. We've blipped other MQTT brokers in the past like Mosquitto and EMQ. Like EMQ and RabbitMQ, VerneMQ is also based on Erlang/OTP which makes it highly scalable. It scales horizontally and vertically on commodity hardware to support a high number of concurrent publishers and consumers while maintaining low latency and fault tolerance. In our internal benchmarks, we've been able to achieve a few million concurrent connections in a single cluster. While it's not new, we've used it in production for some time now, and it has worked well for us.