Securing with the public broker

I would like to use the Public Broker to start with. But if you subscribe to the “testtopic/#” there, you will also see many private messages.

I would use a uuid as the root topic. Can someone see my root topic and read the messages?

And would this be different with another MQTT broker? My small service should be able to send private messages, but this only makes sense if they are secured.

Hi @mchotti,

Welcome to the HiveMQ Community! We’re truly delighted to have you join us, especially given your keen interest in MQTT and the HiveMQ broker. It’s always refreshing to see new users like yourself enriching our community.

Regarding your inquiry, let me shed some light on the distinction between the public broker,, and the HiveMQ Cloud broker (

The public broker is accessible to anyone, allowing clients to subscribe to any topic and receive messages published to that topic. If someone possesses the UUID you’ve used as a topic, they can access the messages.

In contrast, the HiveMQ Cloud broker operates differently. It exclusively supports secure (TLS) connections and mandates MQTT clients to use access credentials (username and password). You can initiate your journey with a Serverless (Free) broker. For a comprehensive understanding of supported features and any limitations, you can refer to our pricing page here: HiveMQ Pricing – Self-Managed MQTT Platform & Full-Managed MQTT Platform.

Please feel free to explore further or reach out if you have any additional questions.

Warm regards,
Dasha from HiveMQ Team