MQTT is the most widely used protocol for sending IoT sensor data to a cloud platform. A device publishes temperature readings to a topic like building/floor3/zone-a/temp. Any application subscribed to that topic receives the reading automatically. It is designed to work reliably on slow, unreliable connections.
MQTT uses a broker as a central hub between devices and applications. The 2-byte fixed header keeps bandwidth overhead minimal.
- Three QoS levels – 0: fire-and-forget, 1: at-least-once delivery, 2: exactly-once delivery
- Last Will and Testament – broker publishes a ‘device offline’ message if a client disconnects without closing the session properly
- Port 1883 – standard; port 8883 for MQTT over TLS (encrypted, required for cloud connections)
- Compatible platforms – AWS IoT Core, Azure IoT Hub, Google Cloud IoT, and all major private brokers (Mosquitto, HiveMQ, EMQX)
In the catalogue: Protocol gateways