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

> less@4.9.1 ships CommonJS and ESM builds. Dual package — require() works on every Node.js version we test; import works too.

Leaner CSS

Last verified Sep 9, 2026 against less@4.9.1.

less publishes both a CommonJS entry and a native ESM entry (ESM added in 4.6.0). require("less") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=18. import "less" works alongside it.

## What to do

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

## Facts

- Latest: 4.9.1 (Sep 2, 2026)
- Module format: Dual (CommonJS + ESM)
- Last CommonJS version: 4.9.1
- Native ESM since: 4.6.0
- TypeScript types: @types/less
- Node engines: >=18
- Weekly downloads: 7.5M
- License: Apache-2.0

## Runtime test results for less@4.9.1

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

| Runtime | require("less") | import "less" |
|---|---|---|
| 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 less

ES modules:

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

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

CommonJS:

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

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (110 versions; the newest 60 shown).

| Versions | Format | First published |
|---|---|---|
| 4.6.1 – 4.9.1 | Dual (CommonJS + ESM) | Mar 10, 2026 |
| 4.6.0 | ESM-only | Mar 10, 2026 |
| 2.5.3 – 4.5.1 | CommonJS | Sep 25, 2015 |

## Frequently asked

**Is less ESM-only?**

less@4.9.1 ships CommonJS and ESM builds. less publishes both a CommonJS entry and a native ESM entry (ESM added in 4.6.0). require("less") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=18. import "less" works alongside it.

**Can I require less?**

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

**Does less work in Bun?**

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

**Does less ship TypeScript types?**

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

## Links

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

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