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MQTT stands for Message Queue Telemetry Transport.

MQTT is a lightweight message queuing and transport protocol.  MQTT, as its name implies, is suited for the transport of telemetry data (sensor and actor data).

MQTT is very lightweight and thus suited for M2M (Mobile to Mobile),WSN(Wireless Sensor Networks) and ultimately IoT (Internet of Things) scenarios where sensor and actor nodes communication with applications through the MQTT message broker.

Example :

Light sensor continuously sends sensor data to the broker.

Building control application receives sensor data from the broker and decides to activate the blinds.

Application sends a blind activation message to the blind actor node through the broker.



MQTT is a good fit for embedded WiFi solutions because it is a lightweight protocol. With MQTT, there are 3 main components:

PUBLISHER: Terminal will be make it as a publisher, as it will be publishing sensor data under a specific “Topic”.

BROKER: This is the “middle man” who holds on to the data that is being published. we are using a publicly available MQTT broker that is suitable for prototyping/demo purposes.You can find a complete list of public MQTT brokers.

SUBSCRIBER: In order to subscribe to any data that is being sent by a PUBLISHER, the SUBSCRIBER must be connected to the same BROKER & subscribed to the same topic as the PUBLISHER. As long as these 2 conditions are met, the SUBSCRIBER will be able to receive messages from the PUBLISHER.

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Example :

Above diagram, you can see Embedded Module and Smart phone work as a Client and in between middle man work as a MQTT Server (Broker).

So, both client one by one publishing data through Server only (Not peer to peer).

When Module client publishing data at that time Smart phone make it as a subscriber vice versa.


Public MQTT brokers

While playing around with MQTT and testing applications it is always helpful to have a MQTT broker at hand. A public MQTT broker enables easy setups without setting up your own MQTT broker. We compiled a list of available brokers that can easily be used:

Server Broker Port Websocket Mosquitto 1883 / 8883 n/a HiveMQ 1883 8000 Mosquitto 1883 / 8883 / 8884 8080 / 8081 mosca 1883 80 HiveMQ 1883

Testing against public brokers also ensures that your application can handle various types of topics and payloads. Because most of those public brokers are actively used by many people and you will find lot of messages being published. Also, this will help you to verify that your code is compatible to different broker implementations.



Here, some MQTT applications for demonstration. May helpful in your IoT projects.

1. MQTT Lens (Chrome Web App) :

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Download Link :

It can be easily installed through the Google Chrome Web Store. The tool has a pretty clean interface and supports all the available connection options from the MQTT spec, except persistent sessions. It accepts connections to more than one broker at the same time and colors them differently for easy association. The interface for subscribing, publishing and seeing all received messages is simple and easy to grasp. Sadly there is no possibility to publish retained messages. But although this app is installed via Chrome, it runs as standalone application and can also connect to brokers via the plain MQTT port 1883, which can’t be done by pure JavaScript Web clients. A nice feature is the display of JSON payloads in a pretty way. In summary, MQTT Lens is particularly well suited for people who need basic pub/sub functionality without having power user needs.

 2. MQTTBox (Chrome Web App):

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Download Link :

Developers helper program to create and test MQTT connectivity protocol. Supercharge your MQTT workflow with MQTTBox for Chrome!

MQTTBox apps are also available for Linux, Mac, Web and Windows.

Please check download link:

MQTTBox features:

  1. MQTT Clients
  • Connect to multiple mqtt brokers with TCP or Web Sockets
  • Connect with wide range of mqtt client connection settings
  • Publish/Subscribe to multiple topics
  • Supports Single Level(+) and Multilevel(#) subscription to topics
  • Copy/Republish payload
  • History of published/subscribed messages for each topic
  1. MQTT Load
  • Load test your MQTT broker or MQTT devices
  • Load test both publish or subscribe to a topic by defining message publish/subscribe rate
  • Publish/Subscribe load with upto 6 instances simultaneously
  • Send upto 10 different payloads while publishing one after the other
  • View progress in real time on dashboard
  • View all load test data sent or received in separate window (Includes smart search)
  • View load test results in graphs.
  • Ability to change sampling rates while generating graphs

Please report Feature Requests, Enhancements and Bugs to

Check source code on github:

3. HiveMQ Websocket Client :

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Web Link :

The HiveMQ Websocket Client is a simple and clean tool made by us while implementing the native websocket support for HiveMQ. After websockets were introduced in HiveMQ, we decided to improve this app a little bit and made it available to everybody as open source. This application is also a perfect starting point to build your own app with the Eclipse Paho JavaScript library. It is a full-fledged MQTT client, which supports all common protocol features except persistent session. The visualization of the different subscription is colorized and the predefined defaults make it possible to publish and receive a message with 3 clicks and no input (Connect, Add new Topic Subscription, Publish). It can also connect to local brokers, when using a local IP address or hostname. The tool particularly comes handy when a MQTT connection over Websockets should be tested or a tool is needed without prior installation. Of course the HiveMQ websocket client works in every modern browser and on most operating systems, including iOS and Android.

4. IoT MQTT Dashboard (Google App) :

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Download Link :

If you are looking for an application to manage your (DIY) IoT projects using MQTT protocol, then stop searching, here it is 🙂

With this app, you can easily control any MQTT client devices with very simple configuration steps. Within a minute, you can talk with your best friend Arduino, or you can command your slave ESP8266 to do something…

Highlighted features:

  • Many connections
  • SSL connection
  • Specify your data unit
  • Display numeric values in a real-time updating chart
  • Customizable publication components:
  1.  Text
  2. Button
  3. Switch
  4. Seek bar
  5. Combo box
  6. Color picker
  7. Multi buttons






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