Installed RabbitMQ for use in Python Celery (for task queue and crontab). Was pleasantly surprised it also offered MQTT support.

Was originally planning on using a third-party, commercial combo websocket/push notification service. But between RabbitMQ/MQTT with websockets and Firebase Cloud Messaging, I'm getting all of it: queuing, MQTT pubsub, and cross-platform push, all for free. 🎉

It all runs nicely in Docker and when time to deploy and scale, trust RabbitMQ more since it has solid cluster support.