Practical MQTT guide
What is an MQTT client?
Understand MQTT client basics before choosing a tool.
An MQTT client talks to a broker.
An MQTT client can be a device, service, command-line script, mobile app, or desktop tool. It connects to an MQTT broker, publishes messages to topics, subscribes to topic filters, or does both.
The client role is independent of the interface: firmware, backend services, command-line programs, and desktop tools all follow the same connect, publish, and subscribe model.
A simple test flow.
Create a broker connection, subscribe to `test/#`, publish a message to `test/hello`, and confirm the payload appears in the subscribed message list.
After the basic flow works, add TLS, username/password, retained messages, QoS, and MQTT 5 properties one at a time.
Common questions
How do I connect an MQTT client to a broker?
Enter the broker host, port, client ID, credentials, and TLS settings, then connect and subscribe to a known test topic.
What are MQTT clients used for?
They are used by IoT devices, backend services, desktop debugging tools, and scripts to exchange messages through an MQTT broker.