// mqtt

MQTT

Connect to an MQTT broker over a persistent backend connection, subscribe to topics, and publish messages — all from a request tab, with a live transcript of the traffic.

What It Does

  • Connects to plaintext (mqtt://, default port 1883), TLS (mqtts://, default port 8883), or bare host:port brokers
  • Subscribes to topics, including wildcards like sensors/#
  • Publishes messages with a chosen QoS level and an optional retain flag
  • Supports QoS 0, 1, and 2 for both subscriptions and published messages
  • Optional client ID (auto-generated when blank), username, and password
  • Configurable keep-alive interval
  • Live status indicator with a received-message count and an incoming-message flash
  • Transcript of published and received messages with topics and timestamps

Connecting

  1. Enter the broker URL — mqtt://broker.example.com, mqtts://… for TLS, or host:port
  2. Optionally set a client ID, username, and password
  3. Adjust the keep-alive interval if your broker needs it
  4. Click Connect — the status indicator goes live once connected

Subscribing

  1. Enter a topic filter, e.g. sensors/temperature or sensors/# for a wildcard
  2. Choose the QoS level for the subscription
  3. Subscribe — matching messages stream into the transcript as they arrive

Publishing

  1. Enter the target topic
  2. Choose the QoS level and whether to set the retain flag
  3. Enter the payload and click Publish

Troubleshooting

Cannot connect

  • Check the scheme and port — 1883 for mqtt://, 8883 for mqtts://
  • Verify credentials, and that the broker accepts your client ID

No messages received

  • Confirm the topic filter actually matches the published topics
  • Check that the subscription QoS is acceptable to the broker

Next Steps