How many clients can a MQTT broker handle?

Question

MQTT is a publish/subscribe protocol. Whenever a publisher publishes to a topic, all the subscribers that have subscribed to that topic will get the message via an MQTT broker. I would like to know the maximum number of clients an MQTT broker can handle. Is there any upper limit for that?

Answer 1

HiveMQ has a whitepaper that shows a benchmark of 200 million clients.

They showed 40 million publishers and 160 million consumers IIRC.

This is done with their broker clustering tech which is a feature their premium product has.