MQTT Viewer FAQ

MQTT Viewer is free and open source under the GPL-3.0 licence. There are no paid tiers, trials or accounts.

The full source is published on GitHub at github.com/mqtt-viewer/mqtt-viewer under the GPL-3.0 licence.

MQTT Viewer is a native desktop application for macOS (Apple Silicon and Intel), Windows (x64 and ARM64) and Linux (x86_64 and ARM64). Linux builds ship as AppImage, deb, rpm, Flatpak and a Nix flake.

MQTT Viewer supports MQTT v3.1.1 and MQTT v5, including publishing with MQTT v5 properties.

Connections can use plain TCP, TLS, mutual TLS with client certificates, and WebSocket (ws and wss). Username and password authentication is supported on all of them.

MQTT Viewer keeps up to 10 broker connections open at once, each in its own tab with its own topic tree, history and saved messages.

MQTT Viewer decodes Sparkplug B protobuf payloads into readable JSON, along with Base64 and Hex payloads. PNG, JPEG, GIF, WebP and BMP payloads are rendered as images.

The broker status page reads the $SYS topics that mosquitto, EMQX and VerneMQ publish and shows clients, message rates, retained messages, uptime and health warnings. Brokers that publish no metrics still get client-side message rates.

Numeric fields in a JSON payload, and bare numeric payloads, can be charted live. Charts can be popped out into their own windows.

MQTT Viewer keeps the topic tree that MQTT Explorer made familiar. It adds up to 10 brokers side by side, MQTT v5, a scrubbable message timeline, a broker status page, a topic graph, Sparkplug B decoding, publish history and client logs.

MQTTX is a broad toolkit with a desktop app, a web client and a CLI. MQTT Viewer is a lighter, broker-neutral desktop client built around inspecting and debugging traffic.

The same app ships as a Docker image that serves it to a browser, and as a Home Assistant add-on. There is no built-in login, so it belongs on localhost, a trusted network, or behind an authenticating proxy.

Downloads for macOS, Windows and Linux are at https://mqttviewer.app/download, with source and release notes at https://github.com/mqtt-viewer/mqtt-viewer/releases.