Node.js & Bun Quickstart

Source: src/content/docs/actors/quickstart/backend.mdx Canonical URL: https://rivet.dev/docs/actors/quickstart/backend Description: Get started with Rivet Actors in Node.js and Bun

Prefer to start from a complete project? See the runnable hello-world example.

Steps

Add Rivet Skill to Coding Agent (Optional)

If you're using an AI coding assistant (like Claude Code, Cursor, Windsurf, etc.), add Rivet skills for enhanced development assistance:

npx skills add rivet-dev/skills

Install Rivet

npm install rivetkit

Create Actors and Start Server

Create a file with your actors, set up the registry, and start the server:

import { actor, setup } from "rivetkit";

export const counter = actor({
	state: { count: 0 },
	actions: {
		increment: (c, x: number) => {
			c.state.count += x;
			c.broadcast("newCount", c.state.count);
			return c.state.count;
		},
	},
});

export const registry = setup({
	use: { counter },
});

registry.start();

Run Server

npx tsx --watch index.ts

bun --watch index.ts

deno run --allow-net --allow-read --allow-env --watch index.ts

Your server is now running on http://localhost:6420. Clients connect directly to the Rivet Engine on this port.

Visit http://localhost:6420 in your browser (or point your AI agent at it) to open the Rivet developer tools and inspect your actors live.

Connect To The Rivet Actor

This code can run either in your frontend or within your backend:

TypeScript

import { actor, setup } from "rivetkit";

export const counter = actor({
	state: { count: 0 },
	actions: {
		increment: (c, x: number) => {
			c.state.count += x;
			c.broadcast("newCount", c.state.count);
			return c.state.count;
		},
	},
});

export const registry = setup({
	use: { counter },
});

registry.start();

import { createClient } from "rivetkit/client";
import type { registry } from "./index";

const client = createClient<typeof registry>("http://localhost:6420");

// Get or create a counter actor for the key "my-counter"
const counter = client.counter.getOrCreate(["my-counter"]);

// Call actions
const count = await counter.increment(3);
console.log("New count:", count);

// Listen to realtime events
const connection = counter.connect();
connection.on("newCount", (newCount: number) => {
	console.log("Count changed:", newCount);
});

// Increment through connection
await connection.increment(1);

See the JavaScript client documentation for more information.

React

import { actor, setup } from "rivetkit";

export const counter = actor({
	state: { count: 0 },
	actions: {
		increment: (c, x: number) => {
			c.state.count += x;
			c.broadcast("newCount", c.state.count);
			return c.state.count;
		},
	},
});

export const registry = setup({
	use: { counter },
});

registry.start();

import { createRivetKit } from "@rivetkit/react";
import { useState } from "react";
import type { registry } from "./index";

const { useActor } = createRivetKit<typeof registry>("http://localhost:6420");

function Counter() {
	const [count, setCount] = useState(0);

	// Get or create a counter actor for the key "my-counter"
	const counter = useActor({
		name: "counter",
		key: ["my-counter"]
	});

	// Listen to realtime events
	counter.useEvent("newCount", (x: number) => setCount(x));

	const increment = async () => {
		// Call actions
		await counter.connection?.increment(1);
	};

	return (
		<div>
			<p>Count: {count}</p>
			<button onClick={increment}>Increment</button>
		</div>
	);
}

See the React documentation for more information.

Deploy

Configuration Options

Source doc path: /docs/actors/quickstart/backend

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