Creating your first MQTT request

In this example of an MQTT request, you will connect to a public broker, subscribe to topics, publish messages, and visualize the response.

Create an MQTT request

In Postman, select New > MQTT to create a new request. (In the Postman desktop app, you can also select ⌘+N or Ctrl+N, then select MQTT).

Connect to a broker with Postman

To connect to an MQTT service, you need a broker URL. This example uses the public broker test.mosquitto.org. You can also use any other public broker or a broker hosted on your local machine.

1. Enter test.mosquitto.org as the request URL.
2. Select Connect to connect to the broker.

A message in the response area indicates that you're connected to the broker.

If you're using the Postman web app, use the Postman Desktop Agent to connect to an MQTT broker. See About the Postman Agent for more information.

Subscribe to topics

While connected to the broker, select the Topics tab. This enables you to create, document, and subscribe to multiple topics.

1. In the Topics column, enter my-toys as the topic name.
2. Select Subscribe to subscribe to the topic.

A message appears in the response area indicating that you're subscribed to the topic.

Publish messages

You can use the Message tab to compose and send messages to the broker.

1. Select the Message tab and enter {"age": 2, "number of toys": 5} as the message.
2. Enter my-toys as the topic name.
3. Select Send to publish the message.

An outgoing message appears in the response area indicating that the message was published. Because you have already subscribed to the topic, my-toys, you will also see an incoming message with the same body. Go ahead and send a few more messages counting the number of toys you had growing up.

Visualize the response

Now that you've subscribed to a topic and published a few messages, you can use the Postman Visualizer to view the messages in a more comprehensible format.

1. Switch to the Visualization tab in the response area. You'll see the messages for the age field visualized as a line chart.
2. Select the field name dropdown list to select the field you want to visualize.
3. Select Add to add more fields to the chart and view the changes in the values.
4. Select the icon next to any of the field names to change the chart type.

The visualization changes in real time as you receive newer messages for the same topic.

Next step

Try subscribing to multiple topics at once and publishing messages to them.