{"data":{"slug":"mqtt-js","name":"MQTT.js","tagline":"MIT Node + browser MQTT client — needs a broker","category":"libraries","categoryName":"Libraries","url":"https://github.com/mqttjs/MQTT.js","github":"https://github.com/mqttjs/MQTT.js","pricing":"open-source","hook":"MQTT.js is the Node + browser MQTT *client* when Mosquitto is the broker you still have to run.","whatsGood":"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.","theCatch":"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.","addedAt":"2026-09-10","featured":false,"domain":"Comms","subSpecialty":"Realtime","subcategory":"Realtime","tags":["self-host","permissive","license-unclear","active"],"capabilities":["mqtt","client","browser"],"surfaces":["Self-host"],"ecosystem":["Node.js","Browser"],"licenseModel":"OSS/MIT","githubStars":9122,"starsPerWeek":11,"access":"free","archived":false,"repo":{"createdAt":"2011-04-05","pushedAt":"2026-10-16","license":"NOASSERTION","archived":false,"checkedAt":"2026-10-19"}},"related":[{"slug":"hono","name":"Hono","tagline":"Tiny TypeScript web framework that runs on every runtime"},{"slug":"phaser","name":"Phaser","tagline":"MIT HTML5 2D game framework with scenes, physics, and tilemaps"},{"slug":"pixijs","name":"PixiJS","tagline":"MIT 2D WebGPU/WebGL renderer, not a game engine"},{"slug":"babylonjs","name":"Babylon.js","tagline":"Apache-2.0 3D engine for the web, now on v9"},{"slug":"playcanvas","name":"PlayCanvas","tagline":"MIT WebGL2/WebGPU engine plus an optional hosted Editor"}],"links":{"self":"/api/gems/mqtt-js","html":"/gems/mqtt-js","markdown":"/gems/mqtt-js.md","category":"/api/gems?category=libraries","categoryPage":"/stacks/libraries"}}