NATS

A high-performance messaging system that ships as a single Go binary and adds optional JetStream persistence on top of a fire-and-forget core.

Category: Messaging & Streaming
CNCF maturity: Incubating
Language: Go
License: Apache-2.0
Repository: nats-io/nats-server
Documented at commit: bd058fac (default branch HEAD, source VERSION 2.15.0-dev, nearest release v2.14.2)

What it is

NATS is a publish/subscribe messaging system. Producers send messages to a subject (a dotted string like orders.eu.new), and the server routes each message to every subscriber whose interest matches that subject. Matching uses a subject token tree with wildcards, so subscribers express interest in patterns such as orders.*.new or orders.>.

The core protocol is at-most-once. The server holds nothing on disk, and a message with no current subscriber is dropped. On top of this core, JetStream adds persistence, replay, at-least-once delivery, key/value buckets, and object storage. JetStream stores data in its own append-only file format and replicates across a cluster with Raft, so it needs no external database.

A single nats-server binary covers the full range of deployment shapes: a standalone process, a clustered set of routed servers, a super-cluster of gateways across regions, and leaf nodes that extend a cluster out to the edge. The same connection-handling code serves all of these by tagging each connection with a kind (server/client.go:259).

When to use it

You want low tail latency for request/reply and pub/sub between services, with one binary and no external dependencies.
You run across regions or out to edge devices and want a built-in topology (gateways, leaf nodes) rather than bolting one on.
You need at-least-once delivery, replay, or a key/value store, and want it from the same system through JetStream.
It is a weaker fit when you need Kafka-style partition and offset semantics as a first-class model. Strict per-key ordering combined with horizontal scale means building subject-based partitioning yourself.

In this deep-dive

History: origin, milestones, and why it exists.
Architecture: components and how requests flow.
Adoption & Ecosystem: who runs it and what surrounds it.
Internals: the code paths that matter, read from source.
Getting Started: install and a first working setup.

NATS ​

What it is ​

When to use it ​

In this deep-dive ​

Sources ​

NATS

What it is

When to use it

In this deep-dive

Sources