Mosquitto is an open source implementation of a server for version 5.0, 3.1.1, and 3.1 of the MQTT protocol. It also includes a C and C++ client library, and the mosquitto_pub and mosquitto_sub utilities for publishing and subscribing.

See the following links for more information on MQTT:

• Community page: https://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/

See https://mosquitto.org/download/ for details on installing binaries for various platforms.

If you have installed a binary package the broker should have been started automatically. If not, it can be started with a basic configuration:

mosquitto

Then use mosquitto_sub to subscribe to a topic:

mosquitto_sub -t 'test/topic' -v

And to publish a message:

mosquitto_pub -t 'test/topic' -m 'hello world'

Documentation for the broker, clients and client library API can be found in the man pages, which are available online at https://mosquitto.org/man/. There are also pages with an introduction to the features of MQTT, the mosquitto_passwd utility for dealing with username/passwords, and a description of the configuration file options available for the broker.

Detailed client library API documentation can be found at https://mosquitto.org/api/

To build from source the recommended route for end users is to download the archive from https://mosquitto.org/download/.

On Windows and Mac, use cmake to build. On other platforms, just run make to build. For Windows, see also README-windows.md.

If you are building from the git repository then the documentation will not already be built. Use make binary to skip building the man pages, or install docbook-xsl on Debian/Ubuntu systems.

• c-ares (libc-ares-dev on Debian based systems) - only when compiled with make WITH_SRV=yes
• cJSON - for client JSON output support. Disable with make WITH_CJSON=no Auto detected with CMake.
• libwebsockets (libwebsockets-dev) - enable with make WITH_WEBSOCKETS=yes
• openssl (libssl-dev on Debian based systems) - disable with make WITH_TLS=no
• pthreads - for client library thread support. This is required to support the mosquitto_loop_start() and mosquitto_loop_stop() functions. If compiled without pthread support, the library isn't guaranteed to be thread safe.
• uthash / utlist - bundled versions of these headers are provided, disable their use with make WITH_BUNDLED_DEPS=no
• xsltproc (xsltproc and docbook-xsl on Debian based systems) - only needed when building from git sources - disable with make WITH_DOCS=no

Equivalent options for enabling/disabling features are available when using the CMake build.

Mosquitto was written by Roger Light [email protected]