# Is ws ESM-only? Can you require() it?

> ws@8.21.3 ships CommonJS and ESM builds. Dual package — require() works on every Node.js version we test; import works too.

Simple to use, blazing fast and thoroughly tested websocket client and server for Node.js

Last verified Sep 9, 2026 against ws@8.21.3.

ws publishes both a CommonJS entry and a native ESM entry (ESM added in 8.0.0). require("ws") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=10.0.0. import "ws" works alongside it.

## What to do

1. Nothing to change. require("ws") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=10.0.0. import * as ws from "ws" works alongside it; use named imports for what the ESM entry exports.
2. TypeScript: npm install -D @types/ws

## Facts

- Latest: 8.21.3 (Aug 7, 2026)
- Module format: Dual (CommonJS + ESM)
- Last CommonJS version: 8.21.3
- Native ESM since: 8.0.0
- TypeScript types: @types/ws
- Node engines: >=10.0.0
- Weekly downloads: 238.4M
- License: MIT

## Runtime test results for ws@8.21.3

Installed and executed on Sep 9, 2026 with require("ws") from a CommonJS file and import "ws" from an ES module.

| Runtime | require("ws") | import "ws" |
|---|---|---|
| Node.js 18 | works | works |
| Node.js 20 | works | works |
| Node.js 22 | works | works |
| Node.js 24 | works | works |
| Node.js 26 | works | works |
| Bun 1.4.0 | works | works |

## How to import ws

ES modules:

```js
import * as ws from "ws";
```

Namespace import shown because the ESM entry may have no default export; use named imports for what it exports.

CommonJS:

```js
const ws = require("ws");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (181 versions; the newest 60 shown).

| Versions | Format | First published |
|---|---|---|
| 8.0.0 – 8.21.3 | Dual (CommonJS + ESM) | Jul 28, 2021 |
| 7.4.1 – 7.5.13 | CommonJS | Dec 4, 2020 |

## Frequently asked

**Is ws ESM-only?**

ws@8.21.3 ships CommonJS and ESM builds. ws publishes both a CommonJS entry and a native ESM entry (ESM added in 8.0.0). require("ws") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=10.0.0. import "ws" works alongside it.

**Can I require ws?**

Yes. ws ships a CommonJS entry alongside the native ESM entry. require("ws") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=10.0.0.

**Does ws work in Bun?**

Yes. import "ws" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does ws ship TypeScript types?**

Not bundled. Install the community types with "npm install -D @types/ws".

## Links

- [ws on npm](https://www.npmjs.com/package/ws)
- [Source repository](https://github.com/websockets/ws)
- [HTML version](https://canirequire.com/package/ws/)
- [JSON version](https://canirequire.com/package/ws.json)

---

For scripts and AI agents: any package is at https://canirequire.com/package/<name>/index.md (Markdown) or https://canirequire.com/package/<name>.json (JSON); the site index is https://canirequire.com/llms.txt. Fetch the URL directly; no search needed.