> For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt.

# output.charset

- **Type:** `'ascii' | 'utf8'`
- **Default:** `'utf8'`

The `charset` config sets the [character encoding](https://developer.mozilla.org/en-US/docs/Glossary/Character_encoding) for output files, ensuring they display correctly across different environments.

## UTF8

By default, Rsbuild outputs files encoded in [UTF-8](https://developer.mozilla.org/en-US/docs/Glossary/UTF-8), the most common character encoding for web applications.

```ts title="rsbuild.config.ts"
export default {
  output: {
    charset: 'utf8', // This is the default
  },
};
```

When your web server returns resources, ensure it sends the correct [Content-Type](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type) response header so browsers can parse them correctly.

## ASCII

To use [ASCII](https://developer.mozilla.org/en-US/docs/Glossary/ASCII) encoding for output files, configure it like this:

```ts title="rsbuild.config.ts"
export default {
  output: {
    charset: 'ascii',
  },
};
```

With ASCII encoding, all non-ASCII characters are escaped with backslashes, making files slightly larger and harder to read.

## Notes

The `charset` option only affects files compiled with [SWC](/guide/configuration/swc.md), which includes JavaScript and TypeScript files by default. HTML and CSS files are not affected by this option.

For HTML files, Rsbuild adds a `<meta charset="utf-8">` tag by default. You can change this using the [html.meta](/config/html/meta.md) option.