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Coreflux HUB MQTT Explorer showing Topic Tree with $SYS, eip, plc, and sensors topics, an empty payload viewer with No topic selected, and publish controls with Payload type, QoS, Retain toggle, text input, and Send button

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Why Use the MQTT Explorer?

You need to see what data is flowing through your broker—which topics are active, what payloads look like, and how to send test messages. The built-in MQTT Explorer in the Coreflux HUB lets you subscribe to topics, browse the topic tree, and publish messages without installing MQTT Explorer or any external MQTT client.
An MQTT Explorer built into your Coreflux. Designed to feel as intuitive as the popular MQTT Explorer desktop app — but with zero installation, right inside the HUB.

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When to Use It

  • Viewing device data — Subscribe to sensor or device topics to see live readings (temperature, status, etc.) as they arrive
  • Exploring your topic structure — Browse the Topic Tree to understand which topics exist and how they are organized
  • Verifying Actions — Subscribe to output topics to confirm your LoT Actions are publishing correctly
  • Debugging — Inspect payloads and topic structure in real time
  • Testing — Publish messages to trigger Actions, test Routes, or simulate device data
  • Monitoring broker activity — Watch $SYS topics to check broker health, connected clients, and message throughput

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Accessing the MQTT Explorer

  1. In the HUB top navigation, select MQTT, then MQTT Explorer.
  2. The Topic Tree appears on the left, showing topics as they receive messages.
  3. Select a topic to view its payloads in the right panel.
Animated walkthrough showing how to open the MQTT Explorer from the Coreflux HUB top navigation

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Topic Tree

The Topic Tree shows the hierarchical structure of topics. Topics appear as messages are received. Expand branches to navigate and select a topic to view its payload history in the payload viewer.
Coreflux HUB MQTT Explorer with $SYS/Coreflux expanded showing Actions, Command, Comms, Config, Log, Python, Resources, Routes, Rules subtopics, and the Config topic selected displaying broker configuration JSON payload

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Subscribing to Topics

The MQTT Explorer automatically builds a topic tree as messages arrive. The simplest way to monitor a topic is to click it in the tree — select any topic to see its latest payloads in the right panel. For broader monitoring, use the subscription controls to add a wildcard pattern (e.g., sensors/#). All topics matching the pattern appear in the Topic Tree as messages come in. Expand branches to drill down into subtopics.

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Publishing Messages

To publish a test message:
  1. Select or enter the target topic.
  2. Enter the payload (plain text or JSON).
  3. Click Publish to send the message.
Use this to trigger Actions, test route configurations, or simulate device data.
Coreflux HUB MQTT Explorer showing a published message to $SYS/Coreflux/Command with payload -h, a Message sent success toast, and the sent message displayed in the payload viewer

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Next Steps

Connected Clients

See which clients are connected to your broker.

MQTT Broker Protocol

Learn how MQTT topics and wildcards work.