# What is nstdlib?

> Node.js standard-library modules for any JavaScript runtime.

**nstdlib** is the Node.js standard library, packaged as plain ES modules that
run outside Node. Modules like `path`, `events`, `stream`, `url` and `assert`
work in browsers, workers, bundlers and other JavaScript runtimes, with the
same imports you already know:

```js
import path from "nstdlib/node/path";

path.join("a", "b"); // 'a/b'
```

It isn't a rewrite. nstdlib is built from Node's own source code, so the
modules behave like Node's because they are Node's.

## Who it's for

- **Bundler users.** Every `nstdlib/node/*` module is an ordinary ES module.
  Your bundler can import it, tree-shake it, and use it in place of a `node:`
  import.
- **Workers and edge runtimes.** Cloudflare Workers, service workers and
  other places where Node can't run, but where you still want `path.join()`,
  a real `URL` or an `EventEmitter`.
- **Browsers.** The parts of the standard library that don't need an
  operating system run in a browser tab. The parts that do throw a clear
  error instead of failing silently. See [Usage](/library/usage).
- **Other JavaScript runtimes.** Anything that's neither Node nor a browser.
- **[nstd](/runtime)**, the standalone runtime from this same
  project. It combines nstdlib with a host written in Zig to run real Node
  programs without Node installed.

## How much of Node works?

Modules that are pure JavaScript, like `path`, `events` or `url`, largely
behave like the real thing. Modules that need the operating system, like `fs`
or `net`, need your runtime to provide those features (see
[Host Integration](/library/host-integration)), and have more gaps.

Support also varies within a module: some exports are verified against real
Node, some exist but throw when you call them, and some haven't been tested.
The [API pages](/api) show the measured status of every module.

## nstdlib or nstd?

- **nstdlib** (this section) is a package you install from npm and import in
  your own code.
- **[nstd](/runtime)** is a single executable that runs `.js`
  files without Node installed.

If you want a library to import, you're in the right place. If you want to
run a script without installing Node, you want nstd.