# Is @aws-sdk/middleware-host-header ESM-only? Can you require() it?

> @aws-sdk/middleware-host-header@3.972.45 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

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Last verified Sep 9, 2026 against @aws-sdk/middleware-host-header@3.972.45.

@aws-sdk/middleware-host-header ships CommonJS only. require("@aws-sdk/middleware-host-header") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=20.0.0. import "@aws-sdk/middleware-host-header" also works because Node.js and Bun can import CommonJS from ES modules, but only the default export is guaranteed; named imports depend on Node's static analysis of the module.

It also declares a "module" field, so bundlers such as webpack, Vite and esbuild pick up an ESM build for tree-shaking.

## What to do

1. require("@aws-sdk/middleware-host-header") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=20.0.0.
2. From ES modules use the default import: import middlewareHostHeader from "@aws-sdk/middleware-host-header"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 3.972.45 (Aug 21, 2026)
- Module format: CommonJS
- Last CommonJS version: 3.972.45
- TypeScript types: bundled
- Node engines: >=20.0.0
- Weekly downloads: 40.5M
- License: Apache-2.0

## Runtime test results for @aws-sdk/middleware-host-header@3.972.45

Installed and executed on Sep 9, 2026 with require("@aws-sdk/middleware-host-header") from a CommonJS file and import "@aws-sdk/middleware-host-header" from an ES module.

| Runtime | require("@aws-sdk/middleware-host-header") | import "@aws-sdk/middleware-host-header" |
|---|---|---|
| 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 @aws-sdk/middleware-host-header

ES modules:

```js
import middlewareHostHeader from "@aws-sdk/middleware-host-header";
```

CommonJS:

```js
const middlewareHostHeader = require("@aws-sdk/middleware-host-header");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (215 versions; the newest 60 shown).

| Versions | Format | First published |
|---|---|---|
| 3.901.0 – 3.972.45 | CommonJS | Oct 1, 2025 |

## Frequently asked

**Is @aws-sdk/middleware-host-header ESM-only?**

@aws-sdk/middleware-host-header@3.972.45 is a CommonJS package. @aws-sdk/middleware-host-header ships CommonJS only. require("@aws-sdk/middleware-host-header") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=20.0.0. import "@aws-sdk/middleware-host-header" also works because Node.js and Bun can import CommonJS from ES modules, but only the default export is guaranteed; named imports depend on Node's static analysis of the module.

**Can I import @aws-sdk/middleware-host-header with ES module syntax?**

Yes. import middlewareHostHeader from "@aws-sdk/middleware-host-header" works in Node.js and Bun because they support importing CommonJS modules. Named imports work only when Node.js can statically detect the exports.

**Does @aws-sdk/middleware-host-header work in Bun?**

Yes. import "@aws-sdk/middleware-host-header" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does @aws-sdk/middleware-host-header ship TypeScript types?**

Yes. @aws-sdk/middleware-host-header bundles its own type declarations; no @types package is needed.

## Links

- [@aws-sdk/middleware-host-header on npm](https://www.npmjs.com/package/@aws-sdk/middleware-host-header)
- [Source repository](https://github.com/aws/aws-sdk-js-v3)
- [HTML version](https://canirequire.com/package/@aws-sdk/middleware-host-header/)
- [JSON version](https://canirequire.com/package/@aws-sdk/middleware-host-header.json)

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