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

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

CLI tool for Size Limit

Last verified Sep 9, 2026 against size-limit@13.0.3.

size-limit 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; it declares support for Node.js ^18.0.0 || >=20.0.0.

On Node.js 22.12+ and newer (size-limit@13.0.3 declares Node.js ^22.18.0 || ^24.0.0 || >=26.0.0), require("size-limit") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 22, 24 and 26. Node.js 18 has no require(esm), and size-limit@13.0.3 declares Node.js ^22.18.0 || ^24.0.0 || >=26.0.0, so 18 is outside its supported range anyway.

size-limit@13.0.3 declares engines "^22.18.0 || ^24.0.0 || >=26.0.0", so Node.js 18, 20 are outside its supported range regardless of module format.

## What to do

1. On Node.js 22.12+ and newer (size-limit@13.0.3 declares Node.js ^22.18.0 || ^24.0.0 || >=26.0.0), require("size-limit") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 22, 24 and 26.
2. From a CommonJS file, use a dynamic import inside an async function: const sizeLimit = await import("size-limit"). That works on every Node.js version the package supports (^22.18.0 || ^24.0.0 || >=26.0.0).
3. If you need a synchronous require() or run Node.js 18: npm install size-limit@9.0.0, the last CommonJS release (published Sep 5, 2023); it declares Node.js ^18.0.0 || >=20.0.0.
4. size-limit@13.0.3 declares engines "^22.18.0 || ^24.0.0 || >=26.0.0", so Node.js 18, 20 are unsupported regardless: upgrade Node.js or pin an older release.
5. TypeScript: types are bundled; install nothing extra.

## 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: bundled
- Node engines: ^22.18.0 || ^24.0.0 || >=26.0.0
- Weekly downloads: 1.2M
- License: MIT

## Runtime test results for size-limit@13.0.3

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

| Runtime | require("size-limit") | import "size-limit" |
|---|---|---|
| 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

ES modules:

```js
import * as sizeLimit from "size-limit";
```

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

CommonJS:

```js
// Node.js 22.12+ and newer (verified):
const sizeLimit = require("size-limit");

// Any Node.js version the package supports (^22.18.0 || ^24.0.0 || >=26.0.0), from an async function:
async function main() {
  const sizeLimit = await import("size-limit");
}

// Or pin the last CommonJS release (declares Node.js ^18.0.0 || >=20.0.0):
// npm install size-limit@9.0.0
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (183 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 ESM-only?**

size-limit@13.0.3 is ESM-only. size-limit 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; it declares support for Node.js ^18.0.0 || >=20.0.0.

**Which version of size-limit still supports CommonJS / require()?**

9.0.0 is the last version of size-limit with a CommonJS build; it declares Node.js ^18.0.0 || >=20.0.0. Install it with "npm install size-limit@9.0.0". Every version from 10.0.0 on is ESM-only.

**How do I use size-limit from a CommonJS file?**

From a CommonJS file, use a dynamic import inside an async function: const sizeLimit = await import("size-limit"). That works on every Node.js version the package supports (^22.18.0 || ^24.0.0 || >=26.0.0). On Node.js 22.12+ and newer (size-limit@13.0.3 declares Node.js ^22.18.0 || ^24.0.0 || >=26.0.0), require("size-limit") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 22, 24 and 26. Alternatively pin size-limit@9.0.0 (declares Node.js ^18.0.0 || >=20.0.0).

**Does size-limit work in Bun?**

Yes. import "size-limit" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does size-limit ship TypeScript types?**

Yes. size-limit bundles its own type declarations; no @types package is needed.

## Links

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

---

For scripts and AI agents: any package is at https://canirequire.com/package/<name>/index.md (Markdown) or https://canirequire.com/package/<name>.json (JSON); the site index is https://canirequire.com/llms.txt. Fetch the URL directly; no search needed.