# What works in Nodepod

> Nodepod is the browser-based Node.js runtime behind Codevre's terminal. This page covers what it supports, what it can't do, and how to work within browser limits.

Last updated: October 17, 2026
Source: https://codevre.com/docs/ide/nodepod

[Nodepod](https://github.com/ScelarOrg/Nodepod) runs Node.js programs inside a web page. It isn't a VM or a WebAssembly build of Node. It reimplements Node's APIs in JavaScript on top of an in-memory file system, runs processes as Web Workers, and serves HTTP servers through a service worker. In Codevre it runs on `preview.codevre.dev`, separate from the editor.

## What works

**Node core modules** with full implementations:

`fs`, `path`, `events`, `stream`, `buffer`, `process`, `http`, `https`, `net`, `crypto`, `zlib`, `url`, `querystring`, `util`, `os`, `tty`, `child_process`, `assert`, `readline`, `module`, `timers`, `string_decoder`, `perf_hooks`, `constants`, `punycode`

**npm:** `npm install` fetches from the public registry, resolves versions and checks package integrity, then installs into `node_modules`. `npm run`, `npx` and `package.json` scripts work. Installed packages are cached on your device, so reinstalling is fast.

**Child processes:** `exec`, `execSync`, `spawn` and `fork` work. Each process is a Web Worker.

**HTTP servers:** `http.createServer` and frameworks such as **Express**, **Hono** and **Elysia** listen on virtual ports. Codevre opens a Browser tab when they start. WebSockets to your server are bridged.

**Tools:** **esbuild** (as WebAssembly) and other pure-JS tools such as TypeScript's `tsc`, Prettier and most linters. Dev servers such as Vite may run, but are heavier in the browser.

**Shell:** a bash-like shell with pipes, redirects, variables, `&&` and the common file commands.

**Git:** a built-in implementation. See [Git and Source Control](source-control.md).

## What doesn't work

Some things simply don't exist inside a browser:

| Not available | Why | Use instead |
|---|---|---|
| Native addons (`.node` files), `node-gyp` builds | The browser can't load native binaries | Pure-JS packages |
| `sharp`, `canvas` (node-canvas) | Native | Browser `<canvas>` in the preview, `jimp` |
| `sqlite3`, `better-sqlite3` | Native | `sql.js`, or JSON files |
| `bcrypt` | Native | `bcryptjs` |
| `puppeteer`, `playwright` | Need a real browser binary | Test in the preview |
| Python, Ruby, Go, Docker, system packages | No OS to run them on | JavaScript tools |
| Global installs (`npm i -g`) | No system-wide install location | `npx`, or local devDependencies |
| Raw TCP/UDP sockets, `dgram`, `tls` servers | Browsers only allow `fetch` and WebSockets | HTTP APIs |

**Modules that exist only as stubs:** `dns`, `worker_threads`, `vm`, `v8`, `tls`, `dgram`, `cluster`, `http2`, `inspector`, `domain`, `diagnostics_channel` and `async_hooks`. Code can import them, but they don't do real work. For example, a `BroadcastChannel` from `worker_threads` is a no-op.

**Networking from your code** goes through the browser's networking. Outgoing requests from Node code (`fetch`, `https.get`) use Nodepod's proxying, and browser rules such as CORS can still apply. Some APIs block requests that come from a browser.

**Performance:** big installs and heavy builds run slower than on a native machine and use your device's memory. Very large projects, or many terminals running servers at once, can make the tab sluggish.

## Paths

- Your project lives in the workspace folder. `pwd` in a new terminal shows it; `$CODEVRE_PROJECT_ROOT` holds it.
- `/` is Nodepod's own root, with `/tmp`, `/dev`, `/home` and `/usr/local/bin`. Don't write project paths as `/file.js`. Use paths relative to the project, or `path.join(__dirname, …)`.

## Persistence

- The file system lives in the page. **Save to Codevre** (Ctrl+S) keeps your project.
- `node_modules`, `.npm` and `.cache` aren't saved. They're rebuilt from `package.json` when you reopen the project, using the cache on your device.
- Running processes don't survive a reload or a runtime restart.
- Caches (packages, `node_modules` snapshots, compiled modules) are stored in IndexedDB and, where available, the Origin Private File System. They can grow to several gigabytes; snapshots older than seven days are removed. Clearing site data for `preview.codevre.dev` frees the space.

## Project tips

- Prefer **no-build** front ends served by [localhost:codevre](localhost-codevre.md): `index.html`, `style.css`, `script.js`, with libraries from esm.sh or jsDelivr.
- When you need bundling, use **esbuild** from a small `build.js`. esbuild in Nodepod treats imports it can't resolve as external. A page error like `Dynamic require of "./x.js" is not supported` means an import path is wrong.
- For servers, use plain `http` or Express on port 3000 and send `Cache-Control: no-store`.
- Restart a server after editing its code, or run it with a watcher (`node --watch`).

## Codevre's version

Codevre runs a custom build of Nodepod (`@scelar/nodepod`, loaded from `preview.codevre.dev/nodepod/`). It's mostly the same as upstream. Differences:

- **Git:** UTF-8- and binary-safe clone, push and pull; push that records the commits it creates under GitHub's hashes; push that rejects non-fast-forward updates; pull that refuses to overwrite local changes or diverged history unless forced; and `sparse-checkout`.
- **Credentials:** Git authentication is passed to individual Git commands by the IDE, never through the environment.
- **IDE integration:** the `vre` and `gh` commands, server-ready events for Browser tabs, and DevTools for server previews.

For Nodepod's own documentation, API and source, see the [Nodepod repository](https://github.com/ScelarOrg/Nodepod).