NATS is ephemeral pub/sub only. There is no persistence or replay, but focuses on high performance and messaging patterns like request/reply. Kafka and Pulsar

NATS is ephemeral pub/sub only. There is no persistence or replay, but focuses on high performance and messaging patterns like request/reply. Kafka and Pulsar persist every message and different consumers can replay the stream from their own positions. Pulsar also supports ephemeral pub/sub like NATS with a lot more advanced features. NATS does have the NATS Streaming project for persistence and replay but it has scalability issues. They're working on a new project called Jetstream to replace this in the future.