# Is @size-limit/preset-small-lib ESM-only? Can you require() it?

> @size-limit/preset-small-lib@13.0.3 is ESM-only. ESM-only since 10.0.0 — last CommonJS version is 9.0.0.

Size Limit preset for small open source libraries

Last verified Sep 9, 2026 against @size-limit/preset-small-lib@13.0.3.

@size-limit/preset-small-lib dropped its CommonJS build in 10.0.0 (October 2023). The last version with a plain require()-able CommonJS entry is 9.0.0, published Sep 5, 2023.

On Node.js 20.19+, 22.12+ and newer, require("@size-limit/preset-small-lib") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. On Node.js 18, which has no require(esm), require("@size-limit/preset-small-lib") fails with ERR_REQUIRE_ESM.

## What to do

1. On Node.js 20.19+, 22.12+ and newer, require("@size-limit/preset-small-lib") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26.
2. From a CommonJS file, use a dynamic import inside an async function: const presetSmallLib = await import("@size-limit/preset-small-lib"). That works on every Node.js version the package supports.
3. If you need a synchronous require() or run Node.js 18: npm install @size-limit/preset-small-lib@9.0.0, the last CommonJS release (published Sep 5, 2023).
4. TypeScript: no types are available for @size-limit/preset-small-lib; declare the module yourself if you need them.

## Facts

- Latest: 13.0.3 (Jul 30, 2026)
- Module format: ESM-only
- Last CommonJS version: 9.0.0
- ESM-only since: 10.0.0 (Oct 23, 2023)
- TypeScript types: none
- Node engines: not declared
- Weekly downloads: 208K
- License: MIT

## Runtime test results for @size-limit/preset-small-lib@13.0.3

Installed and executed on Sep 9, 2026 with require("@size-limit/preset-small-lib") from a CommonJS file and import "@size-limit/preset-small-lib" from an ES module.

| Runtime | require("@size-limit/preset-small-lib") | import "@size-limit/preset-small-lib" |
|---|---|---|
| Node.js 18 | fails (ERR_REQUIRE_ESM) | 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 @size-limit/preset-small-lib

ES modules:

```js
import * as presetSmallLib from "@size-limit/preset-small-lib";
```

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

CommonJS:

```js
// Node.js 20.19+, 22.12+ and newer (verified):
const presetSmallLib = require("@size-limit/preset-small-lib");

// Any Node.js version the package supports, from an async function:
async function main() {
  const presetSmallLib = await import("@size-limit/preset-small-lib");
}

// Or pin the last CommonJS release:
// npm install @size-limit/preset-small-lib@9.0.0
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (108 versions; the newest 60 shown).

| Versions | Format | First published |
|---|---|---|
| 10.0.0 – 13.0.3 | ESM-only | Oct 23, 2023 |
| 4.10.0 – 9.0.0 | CommonJS | Mar 4, 2021 |

## Frequently asked

**Is @size-limit/preset-small-lib ESM-only?**

@size-limit/preset-small-lib@13.0.3 is ESM-only. @size-limit/preset-small-lib dropped its CommonJS build in 10.0.0 (October 2023). The last version with a plain require()-able CommonJS entry is 9.0.0, published Sep 5, 2023.

**Which version of @size-limit/preset-small-lib still supports CommonJS / require()?**

9.0.0 is the last version of @size-limit/preset-small-lib with a CommonJS build. Install it with "npm install @size-limit/preset-small-lib@9.0.0". Every version from 10.0.0 on is ESM-only.

**How do I use @size-limit/preset-small-lib from a CommonJS file?**

From a CommonJS file, use a dynamic import inside an async function: const presetSmallLib = await import("@size-limit/preset-small-lib"). That works on every Node.js version the package supports. On Node.js 20.19+, 22.12+ and newer, require("@size-limit/preset-small-lib") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. Alternatively pin @size-limit/preset-small-lib@9.0.0.

**Does @size-limit/preset-small-lib work in Bun?**

Yes. import "@size-limit/preset-small-lib" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does @size-limit/preset-small-lib ship TypeScript types?**

No. @size-limit/preset-small-lib ships no type declarations and there is no @types package for it.

## Links

- [@size-limit/preset-small-lib on npm](https://www.npmjs.com/package/@size-limit/preset-small-lib)
- [Source repository](https://github.com/ai/size-limit)
- [HTML version](https://canirequire.com/package/@size-limit/preset-small-lib/)
- [JSON version](https://canirequire.com/package/@size-limit/preset-small-lib.json)

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