Man pages
- mosquitto - running the Mosquitto broker
- mosquitto.conf - the Mosquitto broker configuration file
- mosquitto_passwd - command line utility for generating Mosquitto password files
- mosquitto_pub - command line utility for publishing messages to a broker
- mosquitto_rr - command line utility for simple request/response with a broker
- mosquitto_sub - command line utility for subscribing to topics on a broker
- mosquitto-tls - brief cheat sheet for creating x509 certificates
- mqtt - description of MQTT features
libmosquitto API
Other
- Authentication methods - details on the different authentication options available.
- Dynamic Security plugin - details of using the Dynamic Security authentication and access control plugin.
- Using the snap package - specific instructions on installing and configuring the Mosquitto snap package.
- Migrating from 1.x to 2.0 - details of changes needed to migrate to version 2.0.
Third party
These are some Mosquitto documentation hosted by third parties.
- docs.cedalo.com - includes documentation for both Mosquitto and Eclipse Streamsheets
- Steve's internet guide - a broad range of documentation and examples covering Mosquitto and the Paho Python client, amongst others.