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Eclipse Mosquitto

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:

Mosquitto project information is available at the following locations:

There is also a public test server available at


See for details on installing binaries for various platforms.

Quick start

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


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 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

Building from source

To build from source the recommended route for end users is to download the archive from

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

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.

Build Dependencies

  • 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]