Small MQTT client/sniffer

Displays incoming messages from a MQTT broker in a scrolling console window and allows for publishing or subscribing to single topics. Useful for debugging purposes when working with MQTT setups. Uses MQTT protocol version 3.1.1. Supports QoS and “Retain” flags. Can subscribe to wildcard (“#”,“+”) topics. Supports authentication via user/password, and transport encryption over SSL/TLS.

NOT IMPLEMENTED are: Certificate-based client authentication, WebSocket protocol, or the (old) MQTT protocol version 2.4.

Usage: input your desired MQTT broker address (URL or IP) and port into the “Settings” tab, and define a topic. Click “save” and you will be taken to the “Subscribe” tab, where you can connect or disconnect to the MQTT broker. Messages are shown in realtime.

Notes: Subscribing to “#” (wildcard, all topics) on a public MQTT broker might result in the app’s responsiveness becoming sluggish due to the amount of messages it needs to process, and might require to close and re-start the app. Subscribing to all (wildcard) topics on a public broker (as shown in the screenshot) is therefore not advised.

Due to app container restrictions on windows 10, you can NOT use this app to connect to a broker running on the same machine - only connections to other machines are posssible.