# MQTT Viewer

> MQTT Viewer is a free, open-source, cross-platform desktop MQTT client for macOS, Windows, and Linux. It connects to multiple MQTT brokers at once over TCP, TLS/SSL, mutual TLS, and WebSocket, visualizes topics in a live tree and an interactive timeline, decodes Sparkplug B, Base64 and Hex payloads, filters messages, and re-publishes from history — with full MQTT v3.1.1 and v5 support.

Key facts:
- License: GPL-3.0 (open source). Source: https://github.com/mqtt-viewer/mqtt-viewer
- Price: free. All features are available at no cost.
- Platforms: macOS (Apple Silicon & Intel), Windows, Linux (x86_64 & ARM64).
- Protocols: MQTT v3.1.1 and v5; TCP, TLS/SSL, mutual TLS (client certificates), WebSocket (ws/wss).
- Built with Go, Svelte and the Wails framework.

## Pages
- [Home](https://mqttviewer.app/): Overview, features and screenshots.
- [Download](https://mqttviewer.app/download): Downloads for macOS, Windows and Linux.
- [Download for Mac](https://mqttviewer.app/download/mac): Apple Silicon and Intel builds.
- [Download for Windows](https://mqttviewer.app/download/windows): Portable 64-bit build (.zip) for Windows 10 and 11.
- [Download for Linux](https://mqttviewer.app/download/linux): portable x86_64 (Intel/AMD) and ARM64 builds.
- [FAQ](https://mqttviewer.app/faq): Common questions about price, license, platforms and protocols.
- [Compare MQTT clients](https://mqttviewer.app/compare): MQTT Viewer vs MQTTX vs MQTT Explorer vs MQTT.fx.
- [MQTT Explorer alternative](https://mqttviewer.app/mqtt-explorer-alternative): A modern, maintained alternative to MQTT Explorer.
- [MQTT.fx alternative](https://mqttviewer.app/mqtt-fx-alternative): A free, open-source replacement for MQTT.fx.
- [MQTTX alternative](https://mqttviewer.app/mqttx-alternative): A lightweight, broker-neutral alternative to MQTTX.

## Guides
- [Best free MQTT clients in 2026](https://mqttviewer.app/best-mqtt-clients): Comparison of the leading MQTT desktop clients.
- [Debug ESP32 / ESP8266 MQTT messages](https://mqttviewer.app/use-cases/esp32-mqtt-debugging): Verify what your device publishes.
- [MQTT debugging for Home Assistant](https://mqttviewer.app/use-cases/home-assistant-mqtt): Inspect all broker traffic from Home Assistant.
- [MQTT glossary](https://mqttviewer.app/learn/mqtt-glossary): Plain-English definitions of MQTT concepts (QoS, retained messages, LWT, topics & wildcards).

## Source
- [GitHub repository](https://github.com/mqtt-viewer/mqtt-viewer): Source code, issues and releases.
- [Releases](https://github.com/mqtt-viewer/mqtt-viewer/releases): Download the latest version and read release notes.

## Contact
- Email: sam@mqttviewer.app