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

> std-env@4.2.0 is ESM-only. ESM-only since 4.0.0 — last CommonJS version is 3.10.0.

Runtime agnostic JS utils

Last verified Sep 9, 2026 against std-env@4.2.0.

std-env dropped its CommonJS build in 4.0.0 (March 2026). The last version with a plain require()-able CommonJS entry is 3.10.0, published Oct 14, 2025.

On Node.js 20.19+, 22.12+ and newer, require("std-env") 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("std-env") fails with ERR_REQUIRE_ESM.

## What to do

1. On Node.js 20.19+, 22.12+ and newer, require("std-env") 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 stdEnv = await import("std-env"). That works on every Node.js version the package supports.
3. If you need a synchronous require() or run Node.js 18: npm install std-env@3.10.0, the last CommonJS release (published Oct 14, 2025).
4. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 4.2.0 (Jul 7, 2026)
- Module format: ESM-only
- Last CommonJS version: 3.10.0
- ESM-only since: 4.0.0 (Mar 10, 2026)
- TypeScript types: bundled
- Node engines: not declared
- Weekly downloads: 97.9M
- License: MIT

## Runtime test results for std-env@4.2.0

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

| Runtime | require("std-env") | import "std-env" |
|---|---|---|
| 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 std-env

ES modules:

```js
import * as stdEnv from "std-env";
```

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 stdEnv = require("std-env");

// Any Node.js version the package supports, from an async function:
async function main() {
  const stdEnv = await import("std-env");
}

// Or pin the last CommonJS release:
// npm install std-env@3.10.0
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (37 versions; the newest 37 shown).

| Versions | Format | First published |
|---|---|---|
| 4.0.0 – 4.2.0 | ESM-only | Mar 10, 2026 |
| 3.0.0 – 3.10.0 | Dual (CommonJS + ESM) | Nov 3, 2021 |
| 1.0.0 – 2.3.1 | CommonJS | Mar 30, 2018 |

## Frequently asked

**Is std-env ESM-only?**

std-env@4.2.0 is ESM-only. std-env dropped its CommonJS build in 4.0.0 (March 2026). The last version with a plain require()-able CommonJS entry is 3.10.0, published Oct 14, 2025.

**Which version of std-env still supports CommonJS / require()?**

3.10.0 is the last version of std-env with a CommonJS build. Install it with "npm install std-env@3.10.0". Every version from 4.0.0 on is ESM-only.

**How do I use std-env from a CommonJS file?**

From a CommonJS file, use a dynamic import inside an async function: const stdEnv = await import("std-env"). That works on every Node.js version the package supports. On Node.js 20.19+, 22.12+ and newer, require("std-env") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. Alternatively pin std-env@3.10.0.

**Does std-env work in Bun?**

Yes. import "std-env" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does std-env ship TypeScript types?**

Yes. std-env bundles its own type declarations; no @types package is needed.

## Links

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

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