NATS JetStream

JetStream is the persistence layer for NATS that provides at-least-once delivery, stream replication, and consumer state management.

JetStream transforms NATS from a fire-and-forget messaging system into a distributed data store capable of handling millions of messages per second. It implements a pull-based consumer model (ideal for horizontal scaling) and supports policy-based retention (limits by age, size, or message count). By using a Raft-based consensus algorithm, JetStream ensures data consistency across 3 or 5 node clusters. It handles complex patterns like horizontal load balancing, key-value storage, and object storage through a single binary. This is the go-to choice for developers needing durable message offsets and replay capabilities without the operational overhead of Kafka.

https://docs.nats.io/nats-concepts/jetstream