`postMessage(message, transfer)` (or `{ transfer }`) moves ArrayBuffers,
MessagePorts, streams and the rest to the target app instead of copying
them. The second argument is optional, so existing callers are unchanged.
The transfer list rides in the message body as well as the real transfer
list: structured clone's memory map keeps those objects identical to the
ones inside `contents`, which is how the desktop picks them out mid-relay
and keeps transferring them onward rather than leaving copies behind. Both
`messageToApp` paths carry it — the direct iframe relay and the connection
path that `launchApp()` between apps actually uses.
The desktop forwards the list as-is and lets postMessage judge it. A list
that arrived through the SDK was already validated by the browser on the
first hop, and validating again here would mean an allowlist of
transferable types that silently downgrades an unrecognised one to a copy.
A bad list only reaches us from an app that hand-wrote the envelope; that
throws without detaching anything, and is caught so it cannot escape
`ipc_listener` as an unhandled rejection.
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Puter.js
Learn More · Docs · Tutorials · Examples · X
Puter.js gives you auth, cloud storage, database, AI, and more through a single JavaScript library. It is the go-to backend for AI-generated apps.
There is nothing to configure, no API keys, no infrastructure to set up, whether you write the code yourself or have your AI tool do it. Tools like Claude Code, Codex, OpenCode, Lovable, and Replit can generate complete, production-ready apps in a single shot with fewer AI tokens.
Installation
NPM:
npm install @heyputer/puter.js
CDN:
Include Puter.js directly in your HTML via CDN in the <head> section:
<script src="https://js.puter.com/v2/"></script>
Usage
Browser
ES Modules
import {puter} from '@heyputer/puter.js';
// or
import puter from '@heyputer/puter.js';
// or
import '@heyputer/puter.js'; // puter will be available globally
CommonJS
const {puter} = require('@heyputer/puter.js');
// or
const puter = require('@heyputer/puter.js');
// or
require('@heyputer/puter.js'); // puter will be available globally
Node.js (with Auth Token)
const {init} = require("@heyputer/puter.js/src/init.cjs"); // NODE JS ONLY
// or
import {init} from "@heyputer/puter.js/src/init.cjs";
const puter = init(process.env.puterAuthToken); // uses your auth token
const puter2 = init(process.env.puterAuthToken2); // use some other auth token
Node.js (with Auth Token + Web Login)
const {init, getAuthToken} = require("@heyputer/puter.js/src/init.cjs");
// or
import {init, getAuthToken} from "@heyputer/puter.js/src/init.cjs";
const authToken = await getAuthToken(); // performs browser based auth and retrieves token (requires browser)
const puter = init(authToken); // uses your auth token
Usage Example
After importing, you can use the global puter object:
// Print a message
puter.print('Hello from Puter.js!');
// Chat with GPT-5 nano
puter.ai.chat('What color was Napoleon\'s white horse?').then(response => {
puter.print(response);
});
Starter Templates
You can also use one of the following templates:
- Client-side projects: Angular, React, Next.js, Vue.js, Vanilla.js
- Node.js + Express: Node.js + Express template
Setting Custom Origins
By default puter.js uses the official Puter API and GUI origins. You can customize these origins by setting global variables before importing the SDK like so:
// For API origin
globalThis.PUTER_API_ORIGIN = 'https://custom-api.puter.com';
// For GUI origin
globalThis.PUTER_ORIGIN = 'https://custom-gui.puter.com';
import {puter} from '@heyputer/puter.js'; // or however you import it for your env
Documentation & Community
License
Apache-2.0