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

> is-buffer@2.0.5 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

Determine if an object is a Buffer

Last verified Sep 9, 2026 against is-buffer@2.0.5.

is-buffer ships CommonJS only. require("is-buffer") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4. import "is-buffer" 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.

## What to do

1. require("is-buffer") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4.
2. From ES modules use the default import: import isBuffer from "is-buffer"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/is-buffer

## Facts

- Latest: 2.0.5 (Nov 3, 2020)
- Module format: CommonJS
- Last CommonJS version: 2.0.5
- TypeScript types: @types/is-buffer
- Node engines: >=4
- Weekly downloads: 36.0M
- License: MIT

## Runtime test results for is-buffer@2.0.5

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

| Runtime | require("is-buffer") | import "is-buffer" |
|---|---|---|
| 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 is-buffer

ES modules:

```js
import isBuffer from "is-buffer";
```

CommonJS:

```js
const isBuffer = require("is-buffer");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (16 versions; the newest 16 shown).

| Versions | Format | First published |
|---|---|---|
| 1.0.0 – 2.0.5 | CommonJS | Oct 31, 2014 |

## Frequently asked

**Is is-buffer ESM-only?**

is-buffer@2.0.5 is a CommonJS package. is-buffer ships CommonJS only. require("is-buffer") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4. import "is-buffer" 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 is-buffer with ES module syntax?**

Yes. import isBuffer from "is-buffer" 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 is-buffer work in Bun?**

Yes. import "is-buffer" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does is-buffer ship TypeScript types?**

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

## Links

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

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