MQTT Viewer

The MQTT Viewer enables developers and QA engineers to connect to an MQTT broker, subscribe to chosen topics, and observe messages in real time. It focuses on debugging data flows, validating topic routing, and verifying payload formats across devices and environments.
Conceptually, the tool maintains MQTT sessions, handles authentication, manages subscriptions, and renders a stream of messages with topic, payload, timestamp, QoS, and retain flags. It attempts payload decoding to JSON, UTF-8 text, or Base64 to aid rapid comprehension while preserving the original data whenever decoding fails.
Unique value derives from multi-broker support, optional message replay, and export capabilities for reproducible tests. Advanced filters and decoders empower users to isolate problematic topics or payloads and compare traffic between devices. Privacy is emphasized by keeping data local unless an explicit export is performed, ensuring sensitive information is not uploaded by default.
Common use cases include validating sensor telemetry, confirming topic routing, stress-testing QoS flows, and auditing histories during firmware validation. The tool supports MQTT v3.1.1 and v5, TLS or WebSocket transports, and basic authentication, and is not a broker or publisher; it is a focused observability and debugging aid for MQTT traffic.