Modern RabbitMQ scales well. RabbitMQ Streams provide a throughput of millions of messages per second. With native support for MQTT, more than a million users can connect to RabbitMQ: https://www.rabbitmq.com/blog/2023/03/21/native-mqtt

The new Khepri metadata store in RabbitMQ 4.0 allows for even better scalability.

Clients creating server topologies does scale very well with the new Khepri metadata store in RabbitMQ 4.0. Applications having an intimate relationship with their middleware (RabbitMQ) and creating flexible routing topologies is one of main strengths of RabbitMQ! RabbitMQ also allows operators to import (exchange, queue, and binding) definitions on boot. Server topologies can nowadays even be declared via YAML files in Kubernetes (https://github.com/rabbitmq/messaging-topology-operator). This way all the desired state is in one single place and the Kubernetes operator reconciles such that this declaratively declared desired schema is created within RabbitMQ.