MQTTX 1.13.1 Released: AI Agent Skill & MQTT 5.0 Subscription Properties

MQTTX 1.13.1 is now available. This release helps AI coding agents work with MQTTX CLI and adds MQTT 5.0 user properties to Desktop and Web subscriptions. It also improves message exports, adds receive timestamps to the CLI, and fixes topic and payload rendering security issues.

Download MQTTX or read the full 1.13.1 changelog.

AI Agent Skill for MQTTX CLI

The MQTTX repository now includes an installation guide for agents and a mqttx-cli Skill for coding assistants such as Claude Code, Codex, and Cursor. The Skill provides command references and workflows for connection checks, publish/subscribe verification, benchmarks, and data simulation.

After installing MQTTX CLI, add the Skill:

npx skills add emqx/MQTTX --skill mqttx-cli

You can then ask your agent to verify a publish/subscribe round trip against your local broker, with a unique topic and a time limit. See Introducing the MQTTX AI Agent Skill for the installation prompt and a complete example.

This integration runs through MQTTX CLI; it does not require the Desktop application to be open.

MQTT 5.0 subscription user properties

Desktop and Web now let you attach User Properties to a subscription. These key-value pairs travel in the MQTT 5.0 SUBSCRIBE packet and can carry metadata understood by your broker.

Select MQTT 5.0 for your connection, open the subscription dialog, and add the properties alongside the Subscription Identifier. Saved properties appear in the subscription list's topic tooltip, so you can inspect them without reopening the editor.

The properties survive editing and re-subscribing. When you subscribe to an existing topic again, MQTTX updates the saved subscription options to match what it sent to the broker. Repeated keys and empty values are preserved.

For example, an EMQX MQTT Streams subscription can use stream-offset: earliest to request replay from the beginning of a stream. The broker determines how it interprets User Properties; MQTTX sends the values you configure. See the subscription properties change for implementation details.

Clearer and more reliable exports

Message exports now track progress by the number of processed messages. Large exports can show incremental progress even when the data comes from just one connection.

The export fixes also remove duplicated fields from JSON, YAML, and XML output. CSV and Excel use one row per message with separate columns for the topic, payload, QoS, and other fields. Excel groups connections into separate sheets. These changes make exported records easier to inspect and process. See the export fixes.

More control over the client

• Desktop: Korean is available as an interface language. A GPU acceleration setting lets you disable hardware acceleration when troubleshooting rendering problems. Acceleration remains enabled by default, and changing it requires restarting the application. See the GPU setting change.
• Web: The connections pane can be collapsed to give the message view more room.
• CLI: Received messages include a received_at field in UTC ISO 8601 format. This makes it easier to line up MQTT traffic with application logs when diagnosing a problem. See the receive timestamp change.

Security and bug fixes

Topic and payload rendering now escapes content to prevent XSS. The release also adds missing translations and makes Desktop connection-update failures visible in the UI.

For the complete changes and release assets, see the official v1.13.1 release.