MQTT.js
MIT Node + browser MQTT client — needs a broker
Comms / Realtime · OSS/MIT · 9.1k
Reviewed 2026-09-10 · last push 2026-10-16 · repo checked 2026-10-19
What's Good
MIT. mqttjs/MQTT.js (npm `mqtt`). Connect, publish, subscribe with QoS and MQTT 5 paths. Works in Node and browsers; CLI helpers ship with the package. Same “library needs a server” shape as matrix-js-sdk — pair with Mosquitto or any MQTT broker.
The Catch
Client library only — not a broker (that is Mosquitto/HiveMQ/etc.). Browser is MQTT-over-WebSockets only (no raw MQTT TCP from the page). You still provide a reachable broker, credentials, and topic design. Distinct from Mosquitto.
Verdict
MIT MQTT client. Free library; bring a broker — browsers speak WebSockets.
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