Stop Comparing RabbitMQ and Kafka

Every engineering team argues about RabbitMQ vs Kafka like one is "better."

Here's the truth: They solve completely different problems.

Think of it like this:

RabbitMQ moves messages from point A → point B.
Kafka records events as an immutable log you can replay forever.

Once you understand that, everything else clicks.

RabbitMQ is built around queues, routing rules, and delivery guarantees.

It shines when you need the broker to handle complexity on your behalf.

Push model:
The broker actively pushes messages to consumers. Great for low-latency workloads.

Complex broker, simple consumer:
All the routing logic lives in RabbitMQ. Consumers just pick up messages and process them.

Flexible routing:
You get powerful patterns - direct, topic, fanout, headers. Perfect for event-driven apps where routing rules change often.

Protocol polyglot:
Supports AMQP, STOMP, MQTT - it speaks multiple languages.

Where RabbitMQ wins:

✔ Priority queues
✔ Delivery semantics need central control
✔ Routing patterns get messy
✔ Consumers shouldn't handle complexity

Throughput tops out around 4K–10K msgs/sec, but that's fine for transactional workloads.

Kafka isn't a queue. It's a distributed commit log.

Built for scale, throughput, and replay. Things traditional brokers were never designed for.

Pull model:
Consumers fetch messages on demand.

Simple broker, complex consumer:
Kafka's broker does almost nothing except store ordered logs. Consumers handle offsets, parallelism, and state.

Insane throughput:
1 million+ messages per second is normal.

Messages don't disappear:
You can retain them for 7 days, 30 days, or forever. Replay anytime. Huge advantage for analytics, ML pipelines, and auditing.

Partition-based ordering:
Event ordering inside a partition is guaranteed.

Exactly-once semantics:
Achieved via idempotent producers + transactions + read_committed consumers.

Where Kafka wins:

✔ High-throughput pipelines
✔ Events must be replayed anytime
✔ Downstream systems read at different speeds
✔ Ordering guarantees matter
✔ Real-time analytics or streaming architecture

Kafka thrives when your system grows faster than expected.

Choose RabbitMQ if:

Choose Kafka if:

They choose RabbitMQ and treat it like Kafka.

Or they choose Kafka and treat it like RabbitMQ.

Both will fail in production.

RabbitMQ is for moving messages.
Kafka is for recording events.

Don't mix the two mental models.

RabbitMQ is a smart broker with a simple downstream. Kafka is a dumb distributed log with smart downstream.

If you design your system with that mental model, you'll always pick the right one.

Until next time,
Yoshik K.