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.

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. Port 8081 has 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. It is now possible to generate your own certificate.

You are free to use it for any application, but please do not abuse or rely upon it for anything of importance. You should also build your client to cope with the broker restarting.

If you have the mosquitto clients installed try:

Please don't publish anything sensitive, anybody could be listening.