# Is @smithy/signature-v4 ESM-only? Can you require() it?

> @smithy/signature-v4@5.7.3 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

A standalone implementation of the AWS Signature V4 request signing algorithm

Last verified Sep 9, 2026 against @smithy/signature-v4@5.7.3.

@smithy/signature-v4 ships CommonJS only. require("@smithy/signature-v4") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=18.0.0. import "@smithy/signature-v4" 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("@smithy/signature-v4") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=18.0.0.
2. From ES modules use the default import: import signatureV4 from "@smithy/signature-v4"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 5.7.3 (Aug 20, 2026)
- Module format: CommonJS
- Last CommonJS version: 5.7.3
- TypeScript types: bundled
- Node engines: >=18.0.0
- Weekly downloads: 71.8M
- License: Apache-2.0

## Runtime test results for @smithy/signature-v4@5.7.3

Installed and executed on Sep 9, 2026 with require("@smithy/signature-v4") from a CommonJS file and import "@smithy/signature-v4" from an ES module.

| Runtime | require("@smithy/signature-v4") | import "@smithy/signature-v4" |
|---|---|---|
| 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 @smithy/signature-v4

ES modules:

```js
import signatureV4 from "@smithy/signature-v4";
```

CommonJS:

```js
const signatureV4 = require("@smithy/signature-v4");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (102 versions; the newest 60 shown).

| Versions | Format | First published |
|---|---|---|
| 4.1.3 – 5.7.3 | CommonJS | Sep 13, 2024 |

## Frequently asked

**Is @smithy/signature-v4 ESM-only?**

@smithy/signature-v4@5.7.3 is a CommonJS package. @smithy/signature-v4 ships CommonJS only. require("@smithy/signature-v4") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=18.0.0. import "@smithy/signature-v4" 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 @smithy/signature-v4 with ES module syntax?**

Yes. import signatureV4 from "@smithy/signature-v4" 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 @smithy/signature-v4 work in Bun?**

Yes. import "@smithy/signature-v4" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does @smithy/signature-v4 ship TypeScript types?**

Yes. @smithy/signature-v4 bundles its own type declarations; no @types package is needed.

## Links

- [@smithy/signature-v4 on npm](https://www.npmjs.com/package/@smithy/signature-v4)
- [Source repository](https://github.com/smithy-lang/smithy-typescript)
- [HTML version](https://canirequire.com/package/@smithy/signature-v4/)
- [JSON version](https://canirequire.com/package/@smithy/signature-v4.json)

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