Kafka was designed for places with a huge data/log volume (GB/sec or more). From what I understand it's generally The Thing To Use when you have not very many

Kafka was designed for places with a huge data/log volume (GB/sec or more). From what I understand it's generally The Thing To Use when you have not very many (ie: thousands) high-volume sources that have good links. You push stuff into the logs and you can take your time chewing through the log. MQTT was designed for shitloads (hundreds of thousands+) of small devices on bad links connecting to the mothership. Neither of them really are a message queue. I mean, they queue messages, but they have different goals than, say, ActiveMQ or RabbitMQ (which both can be used as a backend for MQTT). Using Kafka for a message queue is overkill. It's more likely that MQTT fits your bill.