MQTT WebSocket Explorer

Connect to any MQTT broker over WebSocket directly from your browser. Subscribe to topics, publish messages, and debug IoT device streams live. No server upload. Perfect for ESP32, home automation, and IoT dev.

Connection Disconnected

Broker URL (paste a full URL to auto-fill)

Presets:

Client ID

Keep-alive (s)

Username

Password

LWT Topic

LWT Payload

QoS

No active subscriptions.

Publish

QoS Retain

Topic Tree 0 topics

Topics discovered from messages will appear here.

Message Log 0 received · 0 sent

Auto-scroll

Connect to a broker and subscribe to topics to see messages here.

About this tool

MQTT (Message Queuing Telemetry Transport) is the pub/sub protocol used by virtually all IoT platforms — ESP32, Arduino, Home Assistant, AWS IoT, Azure IoT Hub, and more. This tool connects your browser directly to any MQTT broker that exposes a WebSocket endpoint (most modern brokers do), letting you subscribe, publish, and debug live device data without installing anything.

Tips for ESP32 / Arduino

Use the HiveMQ or Mosquitto presets for quick testing with public brokers.
Subscribe to # to see every topic — useful for discovering what your device is publishing.
Publish a message to your device's command topic (e.g. cmnd/esp32/power) to trigger actions.
Enable Retain when publishing status values so new subscribers see the last state immediately.
The LWT (Last Will and Testament) payload is sent by the broker if this client disconnects unexpectedly — useful for presence detection.

Public test brokers

HiveMQ — wss://broker.hivemq.com:8884/mqtt
Mosquitto — wss://test.mosquitto.org:8081
Eclipse — wss://mqtt.eclipseprojects.io:443/mqtt

Public brokers are shared — avoid publishing sensitive data.