MQTT is the backbone protocol for IoT communication — lightweight, pub/sub, and designed for unreliable networks.

EMQX is one of the most capable open-source MQTT brokers available, supporting MQTT 3.1, 3.1.1, and 5.0, plus WebSocket transport, built-in authentication, and a web dashboard for monitoring connections and message flows.

Whether you are connecting a handful of ESP sensors or scaling to thousands of devices, EMQX handles it cleanly.

Why EMQX?

  • Standards compliant: Full MQTT 5.0 support alongside 3.1.1, including shared subscriptions, message expiry, and user properties.
  • Built-in dashboard: The web UI at port 18083 gives you a real-time view of connected clients, subscriptions, message rates, and rule engine outputs — no separate monitoring stack required.
  • Rule engine: EMQX ships with a powerful rule engine that can filter, transform, and route messages to databases, HTTP endpoints, Kafka, and more — without writing a single line of broker code.

EMQX with Docker

The EMQX Docker image is self-contained and simple to deploy. It exposes MQTT on the standard ports plus WebSocket and the management dashboard.

docker --version

Docker Compose

#version: '3'

services:
  emqx:
    image: emqx/emqx
    container_name: emqx
    ports:
      - "1883:1883"
      - "8083:8083"
      - "8883:8883"
      - "8084:8084"
      - "18083:18083" #admin/public by default
    restart: always

Port reference:

  • 1883 — MQTT (plain TCP)
  • 8083 — MQTT over WebSocket
  • 8883 — MQTT over TLS
  • 8084 — MQTT over WebSocket with TLS
  • 18083 — Web dashboard

Start the broker:

docker compose up -d

Accessing EMQX

The EMQX web dashboard is available at:

http://localhost:18083

The default credentials are admin / public. Change these immediately after first login. From the dashboard you can configure authentication, create ACL rules, inspect live connections, and set up the rule engine.

To verify the broker is working, point any MQTT client at localhost:1883 and subscribe to a topic:

mosquitto_sub -h localhost -t "test/#" -v

Conclusion

EMQX is a production-grade MQTT broker that is surprisingly easy to run with Docker. It is a solid foundation for any IoT project — from a single-node home lab setup all the way to a multi-node cluster as your device count grows.