Run AI coding CLIs and frameworks in the browser

BrowserCode is a browser-based playground for fast-prototyping full-stack apps and sharing them instantly. It runs on BrowserPod, a multi-language WebAssembly sandbox (Node.js, Rust, and Python in preview), with no installs, no servers, and no cloud compute.

What is BrowserCode?
Quickstart
Make it your own
Embedding
For AI assistants
Breaking BrowserCode
Roadmap

What is BrowserCode?

BrowserCode is a browser-based coding sandbox. It's a working example of BrowserPod, and includes:

Node.js v22, Rust and Python (preview) running in the browser via WebAssembly (more runtimes coming)
A browser-contained, POSIX-like filesystem
Command line tools: bash, git, npm, pnpm, curl, ripgrep and fd
Browser sandbox isolation from the user's operating system
Restricted outbound networking: HTTPS only, to an allowlist that includes the npm registry, Yarn 2+, GitHub (github.com and raw.githubusercontent.com) and the major AI provider APIs
Instant previews over URL via BrowserPod's portal function
Support for Vite, Express.js, Svelte, Next, Nuxt, React and Vue (with Wasm overrides)
Java projects compiled and run in the browser by CheerpJ, in their own Java playground and through embeds

BrowserCode started out as a way to run AI coding CLIs entirely client-side. It's since grown into a full IDE: alongside the CLIs, it can boot and preview web frameworks directly in the browser, so you can prototype an agent's output without ever leaving the tab.

BrowserCode 1.3.0 is our latest beta release. It runs a full code editor, development environment, and unmodified versions of Claude Code, Codex CLI and Pi, completely client-side.

Quickstart

Want to try BrowserCode without installing anything? Use the hosted app.

Go to browsercode.io
BrowserCode will boot instantly, opening with a quick modal tutorial to guide you
Pick an agent from the sidebar, or open the IDE playground to boot a framework template
Claude Code signs in by copying a code from a separate tab; Codex CLI asks for an OpenAI API key, stored in your browser; Pi signs in to the provider of your choice with its own /login

Make it your own

Want to run your own copy, customize the CLIs, or contribute? Clone the repo and run it locally.

Clone the repository and install dependencies

git clone https://github.com/leaningtech/browsercode.git
cd browsercode
npm install

Get a BrowserPod API key at browserpod.io and expose it to the app as VITE_API_KEY
```
echo "VITE_API_KEY=your-key-here" > .env
```
Start the dev server
```
npm run dev
```
Open the printed local URL in a supported browser

Other useful scripts:

npm run build — build a production bundle
npm run preview — preview the production build locally
npm run check — type-check the project
npm run lint / npm run format — lint and format with Prettier + ESLint

CLI availability and behavior are configured in src/lib/config/tools.ts — this is the place to start if you want to add or tweak a CLI.

Embedding

BrowserCode can run inside another site's page through /embed, composed entirely from the query string.

Java embeds (runtime=cheerpj) run on CheerpJ, which does not need cross-origin isolation. They are a plain iframe and can be embedded in any page, with no headers to set:

<iframe
	src="https://browsercode.io/embed?runtime=cheerpj"
	style="width: 100%; height: 600px; border: 0"
></iframe>

Node.js projects, repo clones and agents run on BrowserPod, which needs SharedArrayBuffer and therefore cross-origin isolation. For those, the embedding page must send Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp, and the iframe must carry allow="cross-origin-isolated":

<iframe
	src="https://browsercode.io/embed?framework=vite&view=preview"
	allow="cross-origin-isolated"
	style="width: 100%; height: 600px; border: 0"
></iframe>

Parameters, panes and further detail are in docs/embedding.md.

For AI assistants

If you are an assistant helping someone use BrowserCode, read browsercode.io/llms.txt. One page, no crawling: the URL grammar for templates, repo clones, Java and agent sessions, the embed snippets and which of them need the host page to send isolation headers, and the sandbox constraints that decide whether BrowserCode suits a given project at all.

Breaking BrowserCode

This is BrowserCode beta. Don't be kind to it. Stretch it, bend it, find out what breaks. Here are a few walls you might hit:

At launch, each agent is given an instructions file (CLAUDE.md for Claude Code, AGENTS.md for Codex CLI and Pi) so it understands it is running in a custom environment. However, it may first attempt its default behavior before referencing the file
Pi is installed from npm on its first launch. For Anthropic, pick Copy code login in /login: the default browser login redirects to a localhost callback that can't reach the pod
BrowserCode doesn't yet support native binaries. For more information, see the BrowserPod documentation
Outbound connections are HTTPS-only (port 443) and limited to the allowlist: plain HTTP, SSH (so [email protected] remotes) and other ports are refused, and so is localhost from inside a pod. Portals still expose servers you start in a pod
Agents and Node.js projects require WebAssembly JSPI: Chrome and Edge 137+, Firefox 153+ or Safari 27+. They also don't run on iOS or iPadOS yet, on any browser. Java projects run on CheerpJ and need neither. For maximum compatibility, please use a Chromium browser on the desktop