> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hoppscotch.io/llms.txt
> Use this file to discover all available pages before exploring further.

# MQTT

> Connect to an MQTT broker in Hoppscotch to publish messages, subscribe to topics, and test lightweight publish-subscribe messaging.

## Connect to an MQTT server

1. Enter the MQTT server "**URL**" and click on "**Connect**".

   ```
   wss://test.mosquitto.org:8081
   ```

2. Check the log to see if the connection was successful or not.

3. To test your server add messages under a topic and publish it.

4. Other devices in the server that have subscribed to the topic will get your messages.

5. You can receive messages by subscribing to a topic that another device in the server transmits.

6. Monitor the log for results.

## Sending messages

Write your message in the "**Message**" input field under the "**Communication**" tab and click on the "**Publish**" button. Type in the "**Topic**" input field to send a message with a topic. The message you send will be displayed on the "**Logs**" pane.

## Subscriptions

Click on the "**New Subscription**" button to add a new subscription. Enter the topic name and click on the "**Subscribe**" button to subscribe to the topic. The messages you receive will be displayed on the "**Logs**" pane.

## Troubleshooting

1. Make sure you enter a valid MQTT URL, they always start with the protocol format `ws://`.
2. Do not add invalid/incorrect authorization tokens before you connect to an MQTT server.