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Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

Mosquitto

A free, open-source MQTT broker you can run on your own computer.

Eclipse Mosquitto is an open-source MQTT broker (and the mosquitto_pub / mosquitto_sub command-line clients) used throughout this course on the learner's own machine.

Examples

  • mosquitto -v runs the broker in a terminal and prints every connection and message; it listens on port 1883.

  • Mosquitto 2.x listens on loopback only by default, so a lab file with listener 1883 is needed before an ESP32 on Wi-Fi can connect.

See also

broker client client ID port
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