> ## Documentation Index
> Fetch the complete documentation index at: https://mf2.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Internationalization

> Multi-language support for your application.

`@repo/internationalization` adds multi-language support: locale detection, translation files, pluralization, and date/currency formatting.

## Usage

```tsx theme={null}
import { useTranslation } from "@repo/internationalization";

export function Greeting() {
  const { t } = useTranslation();
  return <h1>{t("dashboard.welcome")}</h1>;
}
```

Pass dynamic values with interpolation:

```tsx theme={null}
const { t } = useTranslation();
t("billing.plan", { plan: "Pro" }); // "Current plan: Pro"
```

## Locale Middleware

```ts theme={null}
import { i18nMiddleware } from "@repo/internationalization";

export default i18nMiddleware({
  defaultLocale: "en",
  locales: ["en", "es", "fr", "de", "ja"],
});
```

## Adding a Locale

Create a JSON file in `packages/internationalization/locales/` and add the locale code to the `locales` array in your middleware.

## Learn More

* [Next.js internationalization guide](https://nextjs.org/docs/app/building-your-application/routing/internationalization)