MQTT Viewer FAQ
Short, straight answers to the questions people ask most about MQTT Viewer — whether it's free, whether it's open source, the protocols and platforms it supports, and how it compares to other clients.
MQTT Viewer is a free, open-source, cross-platform desktop MQTT client. The answers below cover licensing, supported platforms, MQTT versions, security, and how it stacks up against tools like MQTT Explorer and MQTTX. Nothing here is gated behind a sign-up — the app is free to download and use in full.
Questions and answers
Is MQTT Viewer free?
Yes. MQTT Viewer is completely free and open-source under the GPL-3.0 license. There are no paid tiers, trials, accounts, or sign-ups — every feature is available at no cost.
Is MQTT Viewer open source?
Yes. The full source code is published on GitHub under the GPL-3.0 license at github.com/mqtt-viewer/mqtt-viewer, so you can read, build, and contribute to it.
Which platforms does MQTT Viewer run on?
MQTT Viewer is a native desktop application for macOS (Apple Silicon and Intel), Windows, and Linux (x86_64 and ARM64).
Does MQTT Viewer support MQTT 5?
Yes. MQTT Viewer supports both MQTT v3.1.1 and MQTT v5, including publishing messages with MQTT v5 properties and headers.
Does MQTT Viewer support TLS, WebSocket, and client certificates?
Yes. You can connect over plain TCP, TLS/SSL, mutual TLS with client certificates, and WebSocket (ws/wss), with username and password authentication.
Can I connect to more than one broker at the same time?
Yes. MQTT Viewer supports up to 10 simultaneous broker connections, so you can monitor and switch between development, staging, and production environments instantly.
Can MQTT Viewer decode Sparkplug B payloads?
Yes. MQTT Viewer decodes Sparkplug B (protobuf), Base64, and Hex payloads out of the box, so industrial and binary messages are human-readable.
How is MQTT Viewer different from MQTT Explorer?
MQTT Viewer keeps the familiar topic-tree view that MQTT Explorer popularized and adds up to 10 concurrent broker connections, an interactive message timeline, message comparison, payload codecs, and full MQTT v5 support — in an actively developed, open-source app.
How is MQTT Viewer different from MQTTX?
MQTTX is a broad all-in-one toolkit with a desktop app, web client, and CLI. MQTT Viewer is a lighter, focused, broker-neutral desktop client built around visualizing and debugging traffic — free and open-source, with no account required.
Where can I download MQTT Viewer?
Download MQTT Viewer for macOS, Windows, or Linux from https://mqttviewer.app/download. It is free and installs in seconds.
Still have a question?
If your question isn't covered above, the quickest way to find out is to download MQTT Viewer and try it — it's free, installs in seconds, and needs no account. For a feature-by-feature breakdown against other clients, see the full MQTT client comparison, or read why people switch in our MQTT Explorer alternative guide.
MQTT Viewer is free, open-source, and runs on macOS, Windows & Linux.
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