{
  "$type": "site.standard.document",
  "description": "What led me to build a small tool for seeing what happens on my MQTT broker",
  "path": "/writing/keeping-track-of-your-mqtt-broker",
  "publishedAt": "2026-05-22T00:00:00.000Z",
  "site": "at://did:plc:m25hu5wadnbqnt47zep7xza6/site.standard.publication/self",
  "textContent": "MQTT is lightweight, efficient, and often works well as an interoperability layer between systems. I came to appreciate it more than expected,\nespecially after seeing how many software solutions rely on it in places where I would not have assumed MQTT to be involved.\n\nOne thing I kept needing was a simple way to see what was happening on a broker right now.\n\nWhich topics are active? What do the messages look like? Are there unexpected topics or payloads? Are multiple message shapes being published under the same topic?\n\nI first came across [mqtt-explorer](https://mqtt-explorer.com/). It is a great tool and already solves most of this problem.\nThe thing I missed most was better diffing. In practice, I often could not easily see what exactly was being sent, especially when completely different message shapes arrived under the same topic.\n\nThat is why I built [MQTT Radar](https://t128n.github.io/mqtt-radar/).\n\n![MQTT Radar Gif](../../assets/images/mqtt-radar.gif)\n\nIt is a static SPA that connects to a locally running connector. The connector handles the MQTT broker connection, topic subscription, and message collection.\nThe website talks to the connector through local REST endpoints and displays the messages in a way that makes it easier to understand what is happening.\n\nThe tool is intentionally small. It does not try to be a full MQTT workbench. It only tries to answer one question:\n\n> What is going on on my MQTT broker right now?",
  "title": "Keeping Track of Your MQTT Broker"
}