MQTT (Message Queuing Telemetry Transport) is one of the important term in the IoT. It is the standard of IoT Messaging. In this tutorial we will discuss about different MQTT clients. Before diving directly into this, First of all, we need to know what is MQTT clients ?

MQTT Client

An MQTT client is any device (from a micro controller up to a full-fledged server) that runs an MQTT library and connects to an MQTT broker over a network. For example, the MQTT client can be a very small, resource-constrained device that connects over a wireless network and has a bare-minimum library. Both publishers and subscribers are MQTT clients. The MQTT client can also be a typical computer running a graphical MQTT client for testing purposes. Basically, any device that speaks MQTT over a TCP/IP stack can be called an MQTT client.

Now let’s discuss about different MQTT clients:

1. MQTT.fx

MQTT.Fx tool is a desktop tool. It is a JavaFX based client for MQTT protocol. This software is used for debugging and testing MQTT protocol. It comes with the portability of the Java VM and a quite impressive feature set. MQTT.fx is implemented with JavaFX, which is quite obvious, when opening the tool for the first time. Due to the native packaging available for JavaFX, there are binaries for Windows, MacOSX and Linux, which makes the installation a breeze.  It is possible to view publisher and subscriber at the same time by detaching one of the tabs. Also here and there small bugs occur. But regardless of these little things, the listed features makes it definitely one of the best choices, when experimenting with MQTT at the moment.

Features of client

• Predefine message template
• Get status of the broker through the system topic $SYS
• Remember the recently used topics
• Support for JavaScript scripts through Nashorn Engine
• Support log display, display log information in the connection
• Cross-platform desktop with support for Windows, macOS and Linux

2. MQTT-SPY

MQTT-spy has been around since 2014 and as of early 2016 is part of Eclipse Paho and Eclipse IoT. It is an open source utility intended to help you with monitoring activity on MQTT topics. MQTT-spy is a JavaFX application, so should work on any operating system with an appropriate version of Java 8 installed. MQTT-Spy has a very nice way of displaying the basic MQTT publish/subscribe mechanism. It’s been tried on various Linux distributions (Mint, Ubuntu, RedHat) and Windows 7/8.  It makes it easy to publish and subscribe at the same time and there are different tabs for connections to several brokers.  Another handy feature is that it logs every published and received message in the standard output and also into a file. So it is easy to open the file in any text editor and make deeper analysis of the messages.

Features of client

• Support for MQTT and MQTT over WebSocket
• Easy to interact, can publish and subscribe at the same time, connect multiple brokers on different tabs
• Can close different areas of the pub/sub window (publish, new subscriptions, subscriptions and messages) to make room for space currently in use
• The search function allows searching for commonly used MQTT messages, allowing outputting publishing/subscribing messages to standard output or logging to a file for subsequent analysis

3. MQTT Inspector

The MQTT inspector is a really great tool for any iOS device. It is especially suitable for power users. It is possible to create and store connection options, similar to most of the other tools. But this tool also allows to pre-configure publishes and subscriptions as templates.  As a power user tool, it allows switching between a simple message feed, a view grouped by topic and a low-level view. The low level mode shows low-level MQTT command messages and some basic data plus its representation in hex. Another functionality allows to filter the message by their topic, attributes or payload. This is very handy when a lot of messages arrive and only some of them are of interest. As soon as you have understood the handling of MQTT inspector there’s no way it wouldn’t make it onto your iOS device.

Features of client

• Runs on your mobile device, wherever you are
• Gives you access to messages, a topic view and inspects the protocol level
• Filters messages on topic, message content or MQTT flags
• Stores received messages for later review on all detail levels
• Remembers your favorite broker, subscription, publish and filter settings
• Shows messages content as JSON or text if appropriate
• Connects via plain TCP, TLS or over Websockets
• Auto connects to brokers and supports persistent sessions (cleansession=NO)
• Configuration is possible via http or email configuration file

4. MyMQTT

The Android App MyMQTT can be installed via the Google Play Store. It is a useful app that has basic publish and subscribe capabilities. A functionality which differentiates this app from others is its ability to store messages on the phone. The app is still under development and essential features like the different quality of service levels, Last Will and Testament as well as retained messages are missing. However, the last update is almost one year old. So hopefully the announcement of the new MQTT standard this September will bring a new version of this useful app for Android.

Features of client

• Connect to MQTT v3.1 Broker (optional with username and password)
• Subscribe to variouse topics
• Publish messages to a topic
• Save messages
• Filter received Messages

5. MQTT Lens

MQTT Lens is an add-on for the chrome browser that lets you publish messages to an MQTT broker, subscribe to MQTT topics, and receive messages using the chrome web browser. It is also a quite new project, which was developed during the Google Summer of Code 2014. It is easily available on Google Chrome App 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.

Features of client

• Accept connections to multiple mqtt brokers at the same time, with different colors to associate
• The interface for subscribing, publishing and viewing all received messages is very simple and easy to master
• Support for MQTT and MQTT over WebSocket

6. MQTT Explorer

MQTT Explorer is a comprehensive MQTT client that provides a structured overview of your MQTT topics and makes working with devices/services on your broker dead-simple. Currently, it based on CC BY-NC-ND 4.0 protocol open-source, and users can view and use source code at will. Visualization and vertical layered display of topics and dynamic preview are the highlights of MQTT-Explorer. This MQTT Client is optimized to handle thousands of topics and at hundreds of thousands messages per minute. Custom subscriptions can limit the amount of messages MQTT Explorer needs to process, subscriptions can be managed in the advanced connection settings. In very large productive environments brokers may handle an extreme load of topics, subscribing with a wildcard topic is in this scenario not advised.

Visualization and vertical layered display of topics and dynamic preview are the highlights of MQTT-Explorer. Layered view enable this tool to use easily, and has distinguished MQTT Explorer with other outstanding MQTT desktop client.

Features of client

• Visualize topics and dynamic preview of the change of topic
• Delete the reserved topics
• Search/filter topics
• Recursive delete topics
• Difference view of current and previously received messages
• Publish topics
• Draw digital topics
• Retain the historic record of every topic
• Dark/Light topic

7. MQTT X

MQTTX is a cross-platform MQTT 5.0 client tool open source by EMQ. It can run on macOS, Linux and Windows, and supports formatting MQTT payload. MQTT X simplifies the operation logic of the page with the help of chatting software. The user can quickly create a connection to save and establish multiple connection clients at the same time. It is convenient for the user to quickly test the connection of MQTT/TCP、MQTT/TLS, MQTT/ WebSocket Publish / Subscribe functions and other features.

Features of client

• Support MQTT v3.1.1 and MQTT v5.0 protocols
• It supports MQTT over WebSockets
• Message filter is available after clicking subscribed topic
• Storing MQTT broker information, and can select through drop-down

8. MQTT Box

MQTT Box is an MQTT client tool developed by Sathya Vikram, originally only used in Chrome for installation and usage of browser extensions. After rewritten open source, it becomes a desktop-side cross-platform independent software. MQTTBox is a helper program to develop and load test MQTT based clients, brokers, devices, cloud and apps. Every aspect of MQTTBox is specifically designed to maximize development and testing productivity. Together, with MQTT clients and load testing tools integrated, its powerful enough to supercharge your MQTT workflow.

Features of client

• Support installation as Chrome plugin
• Support MQTT, MQTT over WebSocket, multiple TCP encryption connections
• Save the sent history
• Copy/paste messages in history
• Save the history of subscription message
• Simple performance test, testing the load of the broker and viewing the test results through chart visualization

9. MQTT WebSocket Toolkit

MQTT WebSocket Toolkit – MQTT online client tool that supports access from a browser. It facilitates testing the connection, publishing and subscription of MQTT. WebSockets are a good transport method for MQTT because they provide bi-directional, ordered, and lossless communication (WebSockets also leverage TCP).

Features of client

• Online quickly access, without installing, and with the concise and easy-to-use interface
• Support for creating multiple clients, and can retain the information of the client until the next access.

10. Mosquito CLI

Mosquitto is an open-sourced (EPL/EDL license) message broker. Mosquitto provides two command-line MQTT client tools, mosquitto_pub and mosquitto_sub by default after installation. Mosquito CLI has multiple configuration options, supports connections through TLS certificate and a proxy server, supports debug mode, and can get more detailed message information in debug mode.

Features of client

• Thie lightweight command-line tool, support debug mode, easy to install
• Support encrypted and nonencrypted connecting to MQTTQ server
• Easy to test in the remote server