This is It hosts a publicly available Eclipse Mosquitto MQTT server/broker. MQTT is a very lightweight protocol that uses a publish/subscribe model. This makes it suitable for "machine to machine" messaging such as with low power sensors or mobile devices.

For more information on MQTT, see or the Mosquitto MQTT man page.

If you are interested in your own hosted instance of Mosquitto you should look at the Cedalo offering. Cedalo are the company that sponsor the main development of Mosquitto.

The server

The server listens on the following ports:

The encrypted ports support TLS v1.3, v1.2 or v1.1 with x509 certificates and require client support to connect. For ports 8883 and 8884 you should use the certificate authority file ( (PEM format), or (DER format)) to verify the server connection. Ports 8081 and 8886 have a Lets Encrypt certificate, so you should use your system CA certificates or the appropriate Lets Encrypt CA certificate for verification.

Port 8884 requires clients to provide a certificate to authenticate their connection. You can generate your own certificate.

The configuration is available to view.

Authentication and topic access

Unauthenticated clients have access to publish all topics. Clients can also subscribe to all topics with the exception of the literal # topic.

Connecting with the username wildcard will allow a subscription to # to succeed for 20 seconds before being automatically removed. This allows discovery of topics of interest.

The authenticated listeners require a username / password: