[Uptrenda]

The cool thing about MQTT is there's so many servers for it that are completely public -- and intentionally so. You can use it for real time messages but I think it also has quality modes that allow for some persistence.

Some of these servers have stat pages that show how much data they transfer. Usually phenomenal amounts of data. It's pleasing to me as someone doing a lot of stuff with open source networking to have such an establish protocol (instead of say -- 10 crappy ones.) MQTT works and it works well.

[roland35]

Have any examples of public servers?

[Risse]

Helsinki Regional Transport (HSL) has a public server with realtime position of all of their vehicles (buses, trains).

https://digitransit.fi/en/developers/apis/4-realtime-api/veh...

[Scarjit]

HiveMQ has a public one: https://broker.hivemq.com/

[dikei]

I only know this one

https://www.mqtt-dashboard.com/

But a quick Google search will get you some others.