Stateful, Scalable, Realtime Backend Framework

Intro

The modern way to build multiplayer, realtime, or AI agent backends.

Runs on Rivet, Cloudflare Workers, Bun, and Node.js. Integrates with Hono and Redis.

Architecture

• 💾 Persistent, In-Memory State: Fast in-memory access with built-in durability — no external databases or caches needed.
• ⚡ Ultra-Fast State Updates: Real-time state updates with ultra-low latency, powered by co-locating compute and data.
• 🔋 Batteries Included: Integrated support for state, actions, events, scheduling, and multiplayer — no extra boilerplate code needed.
• 🖥️ Serverless & Scalable: Effortless scaling, scale-to-zero, and easy deployments on any serverless runtime.

Features

• 💾 State: Fast in-memory access with built-in durability.
• 💻 Actions: Callable functions for seamless client-server communication.
• 📡 Events: Real-time event handling and broadcasting.
• ⏰ Scheduling: Timed tasks and operations management.
• 🌐 Connections & Multiplayer: Manage connections and multiplayer interactions.
• 🏷️ Metadata: Store and manage additional data attributes.

Everything you need to build realtime, stateful backends

ActorCore provides a solid foundation with the features you'd expect for modern apps.

Feature	ActorCore	Durable Objects	Socket.io	Redis	AWS Lambda
In-Memory State	✓	✓	✓	✓
Persisted State	✓	✓
Actions (RPC)	✓	✓	✓		✓
Events (Pub/Sub)	✓	-	✓	✓
Scheduling	✓	-			-
Edge Computing	✓ †	✓			✓
No Vendor Lock	✓		✓	✓

- = requires significant boilerplate code or external service

† = on supported platforms

Quickstart

Run this command:

npx create-actor@latest

Supported Platforms

• Rivet
• Cloudflare Workers
• Bun
• Node.js

Overview

Create Actor

import { actor, setup } from "actor-core";

const chatRoom = actor({
  state: { messages: [] },
  actions: {
    // receive an action call from the client
    sendMessage: (c, username: string, message: string) => {
      // save message to persistent storage
      c.state.messages.push({ username, message });

      // broadcast message to all clients
      c.broadcast("newMessage", username, message);
    },
    // allow client to request message history
    getMessages: (c) => c.state.messages
  },
});

export const app = setup({
  actors: { chatRoom },
  cors: { origin: "http://localhost:8080" }
});

export type App = typeof app;

Connect to Actor

import { createClient } from "actor-core/client";
import type { App } from "../src/index";

const client = createClient<App>(/* manager endpoint */);

// connect to chat room
const chatRoom = await client.chatRoom.get({ channel: "random" });

// listen for new messages
chatRoom.on("newMessage", (username: string, message: string) =>
  console.log(`Message from ${username}: ${message}`),
);

// send message to room
await chatRoom.sendMessage("william", "All the world's a stage.");

Community & Support

• Join our Discord
• Follow us on X
• Follow us on Bluesky
• File bug reports in GitHub Issues
• Post questions & ideas in GitHub Discussions

License

Apache 2.0