This is an MQTT 5.0 (and 3.1.1) broker.

I'd been using mosquitto for a while and it's worked pretty well, but I wanted a bit more functionality and had already written much of the packet processing in my client library, so putting together something that suits me well was straightforward.

This is currently my production MQTT server with a variety of clients connected with two sites bridging messages with mqtt-bridge and a listener on the internet with TLS using a Let's Encrypt cert.

See the example configuration for an complete example of getting things up and running.