durable-actors README

The project's README from github.com/TerseAI/durable-actors. As one markdown file: README.md.

Durable Actors

an open-source alternative to Cloudflare Durable Objects... with no vendor lock-in, memory limits, and observability built in.

Durable Actors help you build real-time applications like chat systems (e.g. ChatGPT, Codex), collaboration tools (e.g. Notion), and agent swarms (e.g. Devin).

They provide stateful serverless functions, a foundational building block that abstracts away persistence, coordination, and infrastructure challenges in distributed systems.

Live demo · TypeScript documentation · Python documentation

How it works

  1. Define an actor, a class with durable state (i.e. data survives interruptions, errors, and restarts) and serialized execution (i.e. concurrent callers can update it safely). For example:
  1. Generate type-safe clients automatically with the Durable Actors SDK. For now, it supports Python and TypeScript.
  2. Develop locally with one command and later self-host the Durable Actors runtime on GCP.

Quickstart: Multiplayer AI Chat

Teammates share one TeamAgent chat across regions; prompts queue, replies stream to everyone, and conversation state is durably persisted.

1. Create your project

Install Bun 1.4.2+.

bunx durable-actors init my-actors
cd my-actors
bun install
bunx durable-actors dev # Run the server locally on your machine

2. Define an actor

Define and export actors in your actor project’s src/actors.ts, the default entrypoint loaded by durable-actors dev. The runtime loads actors on demand and persists fields marked @Persisted.

For example, a chat history actor:

import { openai } from "@ai-sdk/openai"
import { streamText } from "ai"
import { Actor, type ActorSocket, Interleave, Persisted } from "durable-actors"

type Message = { role: "user" | "assistant"; content: string }

export class ChatHistory extends Actor<null, string, Message[]> {
    @Persisted messages: Message[] = []

    async onConnect(socket: ActorSocket<null, Message[]>) {
        socket.send(this.messages)
    }

    @Interleave // Let other calls run during await, e.g. new connections while a reply streams.
    async onMessage(_socket: ActorSocket<null, Message[]>, text: string) {
        this.messages.push({ role: "user", content: text })
        const result = streamText({ model: openai("gpt-5-mini"), messages: [...this.messages] })
        const reply: Message = { role: "assistant", content: "" }
        this.messages.push(reply)
        this.broadcast(this.messages)
        for await (const chunk of result.textStream) {
            reply.content += chunk
            this.broadcast(this.messages)
        }
    }
}

3. Connect your backend

We make it super easy to integrate the actors into your existing tech stack. Just generate the client and you get a fully type safe contract to interact with.

bunx durable-actors generate

Create a WebSocket connection to one shared chat:

import express from "express"

import { actors } from "../generated/index.js"

export const app = express()

app.post("/api/chat/socket", async (_req, res) => {
    const grant = await actors.ChatHistory.prepareWebsocket({
        actorId: "lobby",
        metadata: null
    })
    res.set("Cache-Control", "no-store").json(grant)
})

4. Connect the frontend

import { useEffect, useRef, useState } from "react"
import { createRoot } from "react-dom/client"

import type { actors } from "../generated/index.js"

function Chat() {
    const socket = useRef<WebSocket>(null)
    const [messages, setMessages] = useState<actors.ChatHistory.Outgoing>([])

    useEffect(() => {
        let active = true
        async function connect() {
            const response = await fetch("/api/chat/socket", { method: "POST" })
            const { websocketUrl } = await response.json()
            if (!active) return
            socket.current = new WebSocket(websocketUrl)
            socket.current.onmessage = event => setMessages(JSON.parse(event.data))
        }
        void connect()
        return () => {
            active = false
            socket.current?.close()
        }
    }, [])

    function send(form: FormData) {
        const text = String(form.get("message")).trim()
        if (!text || socket.current?.readyState !== WebSocket.OPEN) return
        socket.current.send(JSON.stringify(text))
    }

    return (
        <main>
            <div role="log" aria-label="Messages">
                {messages.map((message, index) => (
                    <p key={index}><strong>{message.role}:</strong> {message.content}</p>
                ))}
            </div>
            <form action={send}>
                <input name="message" aria-label="Message" required />
                <button>Send</button>
            </form>
        </main>
    )
}

createRoot(document.getElementById("root")!).render(<Chat />)

For a complete app with error handling and retries, see the AI Chat example.

5. Monitor and debug

Durable Agents provides built-in observability features:

o11y-screenshot

Examples

For complete sample applications, see AI Chat, Collaborative Documents, and Chatroom.

Community

Bug reports, feature requests, documentation fixes, and code contributions are welcome. See the contributing guide for repository setup and checks, and follow our code of conduct.

Use GitHub Issues for bugs, ideas, and questions. Report vulnerabilities privately using our security policy.

Follow development and release notes on GitHub Releases.

License

MIT © 2026 Terse

durable-actors (TerseAI/durable-actors)

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230 ·GitHub
Durable-actors
What is this?Durable Actors is an open-source alternative to Cloudflare Durable Objects for building real-time, multi-agent coordinated systems like chat apps, collaboration tools, and agent swarms, with durable state and WebSocket support.
Is this a hosted service or something I run myself?It is a self-hostable actor runtime with type-safe SDK clients generated for your backend; you develop locally with one command and later self-host the runtime, currently documented for GCP.
How do I get started building an actor?Install Bun 1.4.2+, define actors in your project's 'src/actors.ts' (the entrypoint loaded by 'durable-actors dev'), then generate the type-safe client to connect your backend and frontend over a WebSocket.
Do I need Bun installed before starting?Yes, you need Bun version 1.4.2 or later to create and run a Durable Actors project.
Can I self-host this on any cloud, or just GCP?The README only documents self-hosting the runtime on GCP; other providers are not mentioned.
Which languages can I write clients in?The SDK currently supports Python and TypeScript, with automatic type-safe client generation for both.
What exactly is an 'actor' here?An actor is a class with durable state that survives crashes and restarts, plus serialized execution so concurrent callers can safely update it, like a chat-history actor or a Notion-style document actor.
What kind of apps is this built for?Real-time apps needing coordinated multi-agent state, such as ChatGPT-style chat, Notion-like collaborative documents, and Devin-style agent swarms.
Does it help with debugging actors in production?Yes, it includes built-in observability features for monitoring and debugging actors while they run.
Are there ready-made examples to learn from?Yes, the repo ships complete sample apps for AI Chat, Collaborative Documents, and a Chatroom.
What are similar projects?spring-ai-alibaba, ruflo, jarviscore-framework, harness-sdk, relay, overstory, hive, open-multi-agent
Which topics is it in?actor-model, sqlite3, gcp, multi-agent-systems, bun, collaboration, websocket, agent-orchestration, observability, real-time, distributed-systems, chatbot
Creator
TerseAI
Size
12.5 MB
Stars
230
Updated
CommitOct 18Releasev0.8.1Oct 18
Age
1mo
Commits · 90 Days