MQTT Browser

The MQTT Browser is a built-in tool in the BunkerM dashboard that lets you explore your broker's topic tree and message payloads in real time - directly from your browser, without needing any external MQTT client like MQTT Explorer or mosquitto_sub.

What the MQTT Browser Is

The MQTT Browser connects to your BunkerM broker using your session credentials and provides a graphical interface for:

• Browsing all topics that have retained messages
• Viewing the current payload of any retained topic
• Subscribing to topics to see live message updates
• Publishing messages to any topic
• Exploring the topic hierarchy visually

It is especially useful during development, debugging, and when you want a quick look at what your devices are publishing without leaving the BunkerM dashboard.

Navigating the Topic Tree

The left panel shows a hierarchical tree of all topics that have retained messages on the broker. Topics are organised by their path segments:

home/
  living-room/
    temperature
    humidity
  kitchen/
    temperature
    motion
sensor/
  floor1/
    temp
    humidity

Click any parent node to expand or collapse that branch. Topics with retained messages show their most recent payload.

Viewing a Topic's Payload

Click on any topic name in the tree to view its current retained payload in the detail panel on the right. You will see:

• Payload - the raw message content, displayed as text or formatted JSON where applicable
• QoS level - Quality of Service level (0, 1, or 2)
• Retain flag - always true for topics shown in the tree
• Timestamp - when the last message was received
• Size - payload size in bytes

Subscribing to Topics for Live Updates

The topic tree shows retained messages, but many topics carry live messages without the retain flag. To watch a topic in real time:

1. Click on a topic in the tree, or type a topic pattern in the subscribe box.
2. Click Subscribe.
3. New messages on that topic appear in the message panel as they arrive, with timestamps and payloads.

You can subscribe to wildcard patterns to watch multiple topics at once:

sensor/#          # all topics under sensor/
home/+/temperature  # temperature topics one level under home/

To stop watching, click Unsubscribe next to the subscription entry.

Publishing a Message

1. Click Publish or open the publish panel.
2. Enter the Topic - the full topic path to publish to.
3. Enter the Payload - the message content (text, JSON, or any string).
4. Select the QoS level (0, 1, or 2).
5. Check Retain if you want the broker to retain this message for future subscribers.
6. Click Publish.

The message is published immediately. If you are subscribed to that topic, it appears in the live message feed right away.

Filtering and Searching Topics

When you have many topics, use the search field at the top of the topic tree to narrow down what you see. Type a partial topic path to filter the tree to matching topics only, or use MQTT wildcard patterns. Clear the filter to return to the full topic tree.

Message Metadata Fields

• Topic - full topic path
• Payload - message content
• QoS - 0 = at most once, 1 = at least once, 2 = exactly once
• Retain - whether the broker stores this message for new subscribers
• Timestamp - date and time the message was received
• Size - payload size in bytes

Common Use Cases

• Debugging a device - find its topic and verify the payload it is actually publishing
• Verifying payload format - after a firmware update, confirm the new payload matches what subscribers expect
• Exploring a new setup - browse the retained topic tree to understand what topics are in use
• Manual testing - publish a test command to an actuator topic without needing a separate MQTT client
• Live monitoring - subscribe to # to watch all traffic during a debugging session