Useful new MQTT explorer utility

This is a new and useful bit of software for those wanting to explore what topics and messages are appearing on an MQTT broker. Really impressed so far.


Thanks for bringing it to the community’s attention. I had seen the author’s announcement on the openHAB community forum (where it has been well received) and suggested he do the same here.

That didn’t happen so I guess he is busy improving MQTT-Explorer! :slight_smile: It already has most of what’s needed in an MQTT client but some of the suggested Enhancements, if implemented, will make it an even better tool for managing, and debugging, MQTT.

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This is excellent thank you!

Thanks for the heads up.

working great. I love the hierarchical layout. I think this will nudge out MQTTFx as my go to sniffer tool.

There’s a new version of MQTT-Explorer available (announced by the author in the openHAB forum).

Among several enhancements, now there’s a visual indicator for retained messages. It’s a big red button that also doubles as a convenient tool for purging the retained message. It greatly simplifies the task of explaining to others how to purge a retained message (just push the big red button).


AWESOME TOOL- Thanks for the heads-up.

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This is great been meaning to install all week finally got around to it really handy tool for MQTT debug and retained msg removal is a piece of cake with this. Really good framework to build an amazing tool moving forward.

Why is the Windows executable 150MB Big?!

It contains the electron engine, twice…
The app size has been optimized and will significantly decrease the next release.

The MQTT Explorer becomes mature (v.0.2.0)

Whats new:

  • Connection Manager
  • Recursive topic deletion (Purges retained subtopics with a click)
  • Custom topic subscriptions
  • UI is nicer
  • Fixed some bugs, added some bugs
  • Binary size has been reduced by ~60%

Please report errors, ideas and stuff that just does not feel right:


I really love this utility

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Nice to hear it :tada:
I’m also working on a node-red integration.

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I was going to post this as an Issue in your repo … but since you’re here I wish to inform you of a small bug. Retained messages, published by MQTT Explorer, are not displayed correctly.

How to replicate it:

  1. With MQTT Explorer, connect to an MQTT Broker.
  2. In the Publish pane, enter a topic such as test/data
  3. Leave it in Raw mode (the choice of mode is not significant).
  4. Enter a payload such as 1
  5. Enable the retain option.
  6. Click the Publish button. The new topic test/data will appear in the tree-view.
  7. Expand test/data and click on test.
  8. The payload (1) is displayed in the View pane. However, despite having been published with retain, the UI fails to show the red RETAINED button.

If you disconnect/re-connect to the MQTT Broker, MQTT Explorer refreshes its tree-view and now test/data is shown to contain a retained message (i.e. RETAINED button is displayed).

Thank you for correcting the other display bug where if you deleted a retained message the topic continued to be displayed (and would only disappear if you disconnected-re-connected). Now the topic is immediately removed. Perfect!

This behaviour has always been there. What MQTT Explorer does is show whether the value it is currently displaying is coming from historic (retained) topic or came from a real ‘during this session’ update. Once a new value appears on a ‘retained’ topic the retained flag disappears (even though the topic is retained). If a topic shows ‘retained’ it means it was provided to MQTT-Explorer upon connection and hasn’t had an update since then. I don’t know if this is intentional or a bug.


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Indeed it has. I first noticed it two versions ago but was too lazy to report it. It’s a minor glitch.

The other bug, where the topic continued to be displayed after its retained message was purged, that one was more significant. I was going to report it and then the new version was released (with the correction).

I’m not sure when a client receives a new message from a broker if it can determine whether it is retained or not ? That could be a problem.

It’s neither a bug or a glitch. A message is marked as retained if a client received it from a retained state and it is not a “live” event.
This is a distinction the MQTT broker makes.

In other terms, the App cannot know if a topic is retained when it has been published after a connection was made. The app simply displays the retain flag if it has been received.

There is actually even a tooltip on the retain checkbox that tries to clarify this behavior.

Makes sense… loving this app BTW.
Many thanks for all your effort and implementing the recursive removal of retained topics.

Nice one man, thanks for sharing!

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