Using MQTT Explorer to connect to EMQ X Cloud

This article will take MQTT Explorer as MQTT client test tool to connect to MQTT Cloud Service — EMQ X Cloud. Through this article, you will be able to quickly understand the basic usage of MQTT Explorer and the basic concepts and usage of the MQTT protocol.

Introduction to MQTT Explorer

MQTT Explorer is currently a relatively active MQTT client desktop application, which has always been liked by developers. Its main technology is Electron, which is developed by @thomasnordquist and open-sourced, and follows Creative Commons Public Licenses protocol. GitHub address is

Its main features are:

In particular, some good features are:

MQTT Explorer can meet most development needs, but it also has some disadvantages:

Introduction to EMQ X Cloud

EMQ X Cloud is a fully managed cloud-native MQTT service launched by EMQ company that can connect to a large number of IoT devices and integrate various databases and business systems. As the world’s first fully managed MQTT 5.0 public cloud service, EMQ X Cloud provides MQTT message service with one-stop operation and maintenance management and a unique isolation environment.

In the era of the Internet of Everything, EMQ X Cloud can help users quickly build industry applications for the IoT area and easily realize the collection, transmission, calculation, and persistence of IoT data.

This article will use Free Public MQTT Server provided by EMQ X Cloud as the MQTT server address for this test. The server access information is as follows:

For more details, please visit EMQ X Cloud website or check EMQ X Cloud documentation.

MQTT Explorer usage

Function preview

The main page is shown in the figure below, with the topic search bar and connection configuration at the top. On the lower left of the page, it is the tree structure of the topic, and on the right, it is the Publish column, Subscribe column, Payload column, and History information control column.

MQTT connection/subscription

Initialization page

The configuration page will pop up when you enter MQTT Explorer for the first time.

Create a connection

Click Connections to create a new connection, and fill in the Host as, the port as 1883, and the protocol as MQTT protocol.

Subscribe to a topic

Then, click Advanced. Because EMQ X Cloud prohibits the $SYS topic and the # topic by default, we delete them and enter a test subscription topic with the name test/1, and the result is shown in the figure below.


Finally, click Back to return to the connection configuration page, and click Connect to complete the connection of EMQ X Cloud and the subscription of the topic test/1.

After the connection is successful, you can see that the subscription tree structure has test and 1 nodes, and the status bar at the top right shows that it has been connected, and the title of the topic test/1 is contained on the right.

MQTT message publishing

After the connection is established, enter /test/1 in the topic box at the bottom right corner of the page, and enter some text, and then click Publish to send the message.

Receive subscription messages

After the publish is successful, the message just published will be received in the Value card at the top right.

Receiving history

In the History card at the bottom right corner of the page, you can see the message records received by the relevant subscription topic.

Statistical information

Statistical information will be displayed at the bottom right corner of the page.

Copyright notice: this article was originally written by EMQ. If you want to reprint, please indicate the source clearly. The link of original article:

EMQ is an open-source IoT data infrastructure software provider, delivering the world’s leading open-source MQTT message broker and stream processing database.