Internationalization

Before you get started

Fumadocs is not a full-powered i18n library, it manages only its own components and utilities.

You can use other libraries like next-intl for the rest of your app. Read the Next.js Docs to learn more about implementing I18n in Next.js.

Manual Setup

Define the i18n configurations in a file, we will import it with @/ilb/i18n in this guide.

lib/i18n.ts

import type { I18nConfig } from 'fumadocs-core/i18n';
 
export const i18n: I18nConfig = {
  defaultLanguage: 'en',
  languages: ['en', 'cn'],
};

Pass it to the source loader.

lib/source.ts

import { i18n } from '@/lib/i18n';
import { loader } from 'fumadocs-core/source';
 
export const source = loader({
  i18n,
  // other options
});

And update Fumadocs UI layout options.

app/layout.config.tsx

import { i18n } from '@/lib/i18n';
import type { BaseLayoutProps } from 'fumadocs-ui/layouts/shared';
 
export function baseOptions(locale: string): BaseLayoutProps {
  return {
    i18n,
    // different props based on `locale`
  };
}

Middleware

Create a middleware that redirects users to appropriate locale.

middleware.ts

import { createI18nMiddleware } from 'fumadocs-core/i18n';
import { i18n } from '@/lib/i18n';
 
export default createI18nMiddleware(i18n);
 
export const config = {
  // Matcher ignoring `/_next/` and `/api/`
  matcher: ['/((?!api|_next/static|_next/image|favicon.ico).*)'],
};

See Middleware for customisable options.

Note that this is optional, you can also use your own middleware or the one provided by i18n libraries.

Routing

Create a /app/[lang] folder, and move all files (e.g. page.tsx, layout.tsx) from /app to the folder.

Provide i18n prop like available languages & translations to <RootProvider />. Note that only English translations are provided by default.

app/[lang]/layout.tsx

import { RootProvider } from 'fumadocs-ui/provider';
import type { Translations } from 'fumadocs-ui/i18n';
 
const cn: Partial<Translations> = {
  search: 'Translated Content',
  // other translations
};
 
// available languages that will be displayed on UI
// make sure `locale` is consistent with your i18n config
const locales = [
  {
    name: 'English',
    locale: 'en',
  },
  {
    name: 'Chinese',
    locale: 'cn',
  },
];
 
export default async function RootLayout({
  params,
  children,
}: {
  params: Promise<{ lang: string }>;
  children: React.ReactNode;
}) {
  const lang = (await params).lang;
 
  return (
    <html lang={lang}>
      <body>
        <RootProvider
          i18n={{
            locale: lang,
            locales,
            translations: { cn }[lang],
          }}
        >
          {children}
        </RootProvider>
      </body>
    </html>
  );
}

Pass Locale

Pass the locale to Fumadocs in your pages and layouts.

/app/[lang]/(home)/layout.tsx

import type { ReactNode } from 'react';
import { HomeLayout } from 'fumadocs-ui/layouts/home';
import { baseOptions } from '@/app/layout.config';
 
export default async function Layout({
  params,
  children,
}: {
  params: Promise<{ lang: string }>;
  children: ReactNode;
}) {
  const { lang } = await params;
 
  return <HomeLayout {...baseOptions(lang)}>{children}</HomeLayout>;
}

Search

Configure i18n on your search solution.

Built-in Search (Orama): For Supported Languages, no further changes are needed.

Otherwise, additional config is required (e.g. Chinese & Japanese). See Special Languages.
Cloud Solutions (e.g. Algolia): They usually have official support for multilingual.

Writing Documents

You can add Markdown/meta files for different languages by attending .{locale} to your file name, like page.fr.md and meta.fr.json.

Make sure to create a file for the default locale first, the locale code is optional (e.g. both get-started.mdx and get-started.en.mdx are accepted).

meta.json

meta.cn.json

get-started.mdx

get-started.cn.mdx

Fumadocs only handles navigation for its own layouts (e.g. sidebar). For other places, you can use the useParams hook to get the locale from url, and attend it to href.

import Link from 'next/link';
import { useParams } from 'next/navigation';
 
const { lang } = useParams();
 
return <Link href={`/${lang}/another-page`}>This is a link</Link>;

In addition, the fumadocs-core/dynamic-link component supports dynamic hrefs, you can use it to attend the locale prefix. It is useful for Markdown/MDX content.

content.mdx

import { DynamicLink } from 'fumadocs-core/dynamic-link';
 
<DynamicLink href="/[lang]/another-page">This is a link</DynamicLink>