wcvmNode.js in your browser tab

No backend. Real processes in Web Workers, Node's own runtime, npm install, and dev servers you can preview in an iframe.

Get started

Open Studio

GitHub

Real processes

One Web Worker per PID, with stdout, stderr, stdin and kill(). A child process is another worker, supervised by the kernel.

Node's own runtime

Node v24's lib/ is vendored unmodified on a small native layer written for the browser, so fs, streams, http, net, child_process, zlib, ESM and require(esm) behave like Node.

npm install, in the tab

A built-in npm installs from the real registry into an in-memory filesystem, then npm run starts your scripts.

Dev servers in an iframe

A Service Worker relays an iframe to a server running in the sandbox, WebSockets included, so Vite's hot reload works.

Persistent projects

Optionally mirror the filesystem to the browser's Origin Private File System and restore it on the next load.

Frameworks that run

Vite (React, Vue, Svelte, ...), Next.js, SvelteKit, React Router 7, Astro, Angular, Ember, Express and NestJS, each verified in real Chromium.

Try it live

This runs real Node.js, inside this page. Edit the code and press Run: the process is a Web Worker, and nothing leaves your browser.

Live Node terminalOpen in Studio ↗

node - index.js

index.jsCmd+S / Ctrl+S to run

import os from "node:os";
import { createHash } from "node:crypto";

console.log("Node", process.version);
console.log("platform:", os.platform(), "(in a browser tab)");

const hash = createHash("sha256");
const digest = hash.update("hello from wcvm").digest("hex");
console.log("sha256:", digest.slice(0, 32) + "...");

let total = 0;
for (let i = 1; i <= 5; i++) {
  total += i;
  console.log("tick", i, "sum", total);
}

console.log("done - edit me and hit Run again!");

Terminal

Ready. Edit index.js and press Run.