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

> flatted@3.4.4 ships CommonJS and ESM builds. Dual package — require() works on every Node.js version we test; import works too.

A super light and fast circular JSON parser.

Last verified Sep 9, 2026 against flatted@3.4.4.

flatted publishes both a CommonJS entry and a native ESM entry (ESM added in 3.0.0). require("flatted") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import "flatted" works alongside it.

## What to do

1. Nothing to change. require("flatted") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import * as flatted from "flatted" works alongside it; use named imports for what the ESM entry exports.
2. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 3.4.4 (Jul 30, 2026)
- Module format: Dual (CommonJS + ESM)
- Last CommonJS version: 3.4.4
- Native ESM since: 3.0.0
- TypeScript types: bundled
- Node engines: not declared
- Weekly downloads: 136.1M
- License: ISC

## Runtime test results for flatted@3.4.4

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

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

ES modules:

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

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

CommonJS:

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

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (44 versions; the newest 44 shown).

| Versions | Format | First published |
|---|---|---|
| 3.0.0 – 3.4.4 | Dual (CommonJS + ESM) | May 26, 2020 |
| 0.1.0 – 2.0.2 | CommonJS | Apr 26, 2018 |

## Frequently asked

**Is flatted ESM-only?**

flatted@3.4.4 ships CommonJS and ESM builds. flatted publishes both a CommonJS entry and a native ESM entry (ESM added in 3.0.0). require("flatted") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import "flatted" works alongside it.

**Can I require flatted?**

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

**Does flatted work in Bun?**

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

**Does flatted ship TypeScript types?**

Yes. flatted bundles its own type declarations; no @types package is needed.

## Links

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

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