Getting Started with NATS

Get up and running with NATS in minutes. This guide will walk you through installation, basic setup, and your first NATS application.

Installation

Quick Start with Docker

The fastest way to get NATS running:

docker run -p 4222:4222 -p 8222:8222 nats:latest

This starts NATS Server with:

• Client connections on port 4222
• HTTP monitoring on port 8222

Install NATS Server

macOS

brew install nats-server

Linux

curl -sf https://binaries.nats.dev/nats-io/nats-server/v2@latest | sh
sudo mv nats-server /usr/local/bin/

Windows

Download the latest release from GitHub Releases.

Verify Installation

nats-server --version

Start NATS Server

Basic Server

nats-server

With Monitoring

nats-server -m 8222

Visit http://localhost:8222 to see server metrics.

With JetStream (Persistence)

nats-server -js

Install NATS CLI

The NATS CLI tool helps you interact with NATS:

# macOS
brew install nats-io/nats-tools/nats

# Linux
curl -sf https://binaries.nats.dev/nats-io/natscli/nats@latest | sh
sudo mv nats /usr/local/bin/

Your First NATS Application

Using the CLI

# Subscribe to a subject
nats sub hello &

# Publish a message
nats pub hello "Hello NATS!"

Install Client Libraries

CLI

# The NATS CLI is already installed (see above)
# You can use it directly for pub/sub operations

JavaScript/TypeScript

npm install nats

Go

go get github.com/nats-io/nats.go

Java

Gradle

dependencies {
  implementation 'io.nats:jnats:2.25.2'
}

Maven

<dependency>
    <groupId>io.nats</groupId>
    <artifactId>jnats</artifactId>
    <version>2.25.2</version>
</dependency>

Rust

Cargo.toml

[dependencies]
async-nats = "0.47.0"
tokio = { version = "1", features = ["full"] }

C#/.NET

dotnet add package NATS.Net

See NATS.Net on NuGet for the latest version.

Publisher Example

CLI

#!/bin/bash

# Publish a message to demo.nats.io
nats pub --server=demo.nats.io hello "Hello NATS!"

JavaScript/TypeScript

/*
 * Copyright 2026 The NATS Authors
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// import the connect function from a transport
import { connect } from "@nats-io/transport-deno";

// connect to NATS demo server
const nc = await connect();

// publish a message to the 'hello' subject
nc.publish("hello", "Hello NATS!");
console.log("Message published to hello");

// drain the connection (flushes and closes)
await nc.drain();

Go

package main

import (
	"log"

	"github.com/nats-io/nats.go"
)

func main() {
	// Connect to NATS demo server
	nc, err := nats.Connect("demo.nats.io")
	if err != nil {
		log.Fatal(err)
	}
	defer nc.Close()

	// Publish a message
	err = nc.Publish("hello", []byte("Hello NATS!"))
	if err != nil {
		log.Fatal(err)
	}

	log.Println("Message published to hello")
}

Python

async def main():
    # Connect to NATS demo server
    nc = await client.connect("nats://demo.nats.io")

    # Publish a message to the subject "hello"
    await nc.publish("hello", b"Hello NATS!")
    await nc.flush()

    print("Message published to hello")

    await nc.close()

Java

public static void main(String[] args) {
    try (Connection nc = Nats.connect("nats://localhost:4222")) {
        // Publish a message to the subject "hello"
        byte[] data = "Hello NATS!".getBytes(StandardCharsets.UTF_8);
        nc.publish("hello", data);
        System.out.println("Message published to hello");
    }
    catch (InterruptedException e) {
        // can be thrown by connect
        Thread.currentThread().interrupt();
    }
    catch (IOException e) {
        // can be thrown by connect
    }
}

Rust

// Connect to NATS demo server
let client = async_nats::connect("demo.nats.io").await?;

// Publish a message to the subject "hello"
client.publish("hello", "Hello NATS!".into()).await?;
client.flush().await?;

println!("Message published to hello");

C#/.NET

await using var client = new NatsClient("demo.nats.io");

// Publish a message to the subject "hello"
await client.PublishAsync("hello", "Hello NATS!");

C

// Connect to the NATS server
const char *url = getenv("NATS_URL");

s = natsConnection_ConnectTo(&conn, (url == NULL) ? NATS_DEFAULT_URL : url);

// Publish a message
if (s == NATS_OK)
    s = natsConnection_PublishString(conn, "hello", "Hello NATS!");

if (s == NATS_OK)
    printf("Message published to hello\n");

Subscriber Example

CLI

#!/bin/bash

# Subscribe to messages from demo.nats.io
nats sub --server=demo.nats.io hello

JavaScript/TypeScript

// Subscribe to the "weather.updates" subject; auto-close after 1 message
const sub = nc.subscribe("weather.updates");

// iterate over messages received (sub will end after the first message)
for await (const msg of sub) {
  console.log(`Received: ${msg.string()}`);
  break;
}

Go

package main

import (
	"log"

	"github.com/nats-io/nats.go"
)

func main() {
	// Connect to NATS demo server
	nc, err := nats.Connect("demo.nats.io")
	if err != nil {
		log.Fatal(err)
	}
	defer nc.Close()

	// Subscribe to 'hello'
	_, err = nc.Subscribe("hello", func(msg *nats.Msg) {
		log.Printf("Received: %s", string(msg.Data))
	})
	if err != nil {
		log.Fatal(err)
	}

	log.Println("Listening for messages on 'hello'...")

	// Keep the process running
	select {}
}

Python

async def main():
    nc = await client.connect("nats://demo.nats.io")

    # Asynchronous subscriber - iterate messages in a background task
    async_sub = await nc.subscribe("hello")

    async def async_handler():
        async for msg in async_sub:
            print(f"Asynchronous Subscriber Received: {msg.data.decode()}")

    asyncio.create_task(async_handler())

    # Synchronous subscription
    sync_sub = await nc.subscribe("hello")

    print("Waiting for message on 'hello'")

    # Process messages synchronously
    while True:
        try:
            msg = await sync_sub.next(timeout=1)
            print(f"Synchronous Subscriber Received: {msg.data.decode()}")
        except TimeoutError:
            break

    await nc.close()

Java

public static void main(String[] args) {
    try (Connection nc = Nats.connect("nats://localhost:4222")) {
        // Asynchronous Subscriber requires a dispatcher
        // Dispatchers can be shared
        Dispatcher d = nc.createDispatcher(msg -> {
            System.out.println("Asynchronous Subscriber Received: " +
                new String(msg.getData(), StandardCharsets.UTF_8));
        });

        // Subscribe to 'hello' subject
        d.subscribe("hello");

        // Subscribe to 'hello' synchronously
        Subscription syncSub = nc.subscribe("hello");

        System.out.println("Waiting for message on 'hello'");

        // Process messages
        Message m = syncSub.nextMessage(1000);
        while (m != null) {
            System.out.println("Synchronous Subscriber Received: " +
                new String(m.getData(), StandardCharsets.UTF_8));
            m = syncSub.nextMessage(1000);
        }
    }
    catch (InterruptedException e) {
        // can be thrown by connect
        Thread.currentThread().interrupt();
    }
    catch (IOException e) {
        // can be thrown by connect
    }
}

Rust

// Connect to NATS demo server
let client = async_nats::connect("demo.nats.io").await?;

// Subscribe to the 'hello' subject
let mut subscriber = client.subscribe("hello").await?;
println!("Listening for messages on 'hello'...");

// Process messages
while let Some(msg) = subscriber.next().await {
    println!("Received: {}", String::from_utf8_lossy(&msg.payload));
}

C#/.NET

await using var client = new NatsClient("demo.nats.io");

// Subscribe to 'hello' and process messages
await foreach (var msg in client.SubscribeAsync<string>("hello"))
{
    output.WriteLine($"Received: {msg.Data}");
}

C

// The callback runs for each message received on 'hello'.
static void
onMsg(natsConnection *nc, natsSubscription *sub, natsMsg *msg, void *closure)
{
    printf("Received: %.*s\n",
           natsMsg_GetDataLength(msg), natsMsg_GetData(msg));

    natsMsg_Destroy(msg);
}
    // Connect to the NATS server
    const char *url = getenv("NATS_URL");

    s = natsConnection_ConnectTo(&conn, (url == NULL) ? NATS_DEFAULT_URL : url);

    // Subscribe to 'hello'
    if (s == NATS_OK)
        s = natsConnection_Subscribe(&sub, conn, "hello", onMsg, NULL);

    if (s == NATS_OK)
        printf("Listening for messages on 'hello'...\n");

Running the Examples

CLI

# Terminal 1 - Start subscriber
nats sub hello

# Terminal 2 - Publish messages
nats pub hello "Hello NATS!"
nats pub hello "Welcome to messaging"

# Request-Reply pattern
# Terminal 1 - Start replier
nats reply hello "Hi there!"

# Terminal 2 - Send request
nats request hello "Anyone there?" --timeout=2s

JavaScript/TypeScript

# Terminal 1 - Start subscriber
node subscribe.js

# Terminal 2 - Run publisher
node publish.js

Go

# Terminal 1 - Start subscriber
go run subscribe.go

# Terminal 2 - Run publisher
go run publish.go

Java

It's best to run the examples from your IDE or 
command line where Java is installed.

Clone https://github.com/nats-io/nats.java
and navigate to src/main/java/io/nats/examples/natsIoDoc

Rust

# Terminal 1 - Start subscriber
cargo run --bin subscribe

# Terminal 2 - Run publisher
cargo run --bin publish

C#/.NET

It's best to run the examples from your IDE or
command line where the .NET SDK is installed.

Clone https://github.com/nats-io/nats.net
and navigate to examples/Example.NatsIODocs

Next Steps

Congratulations! You've successfully:

• ✅ Installed NATS Server
• ✅ Published and subscribed to messages
• ✅ Built your first NATS application

What to explore next:

• Core NATS deep dive — hands-on path through the fundamentals
• JetStream deep dive — persistence and streaming
• The full Learn section — guided, runnable chapters
• Request-Reply Pattern — synchronous communication
• Subjects — understanding subject-based messaging

Client Libraries

NATS has official clients for:

• Go
• Java
• JavaScript/TypeScript
• Python
• Rust
• C
• .NET

Resources

• NATS by Example - Interactive examples
• Slack Community - Get help from the community