Mosquitto is an open source implementation of a server for version 5.0, 3.1.1, and 3.1 of the MQTT protocol.

 https://github.com/eclipse/mosquitto

 

Links

See the following links for more information on MQTT:

    Community page: http://mqtt.org/
    MQTT v3.1.1 standard: https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html
    MQTT v5.0 standard: https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html

Mosquitto project information is available at the following locations:

    Main homepage: https://mosquitto.org/
    Find existing bugs or submit a new bug: https://github.com/eclipse/mosquitto/issues
    Source code repository: https://github.com/eclipse/mosquitto

There is also a public test server available at https://test.mosquitto.org/