Usage in Server Components (beta)

Next.js 13 introduces support for React Server Components (opens in a new tab) in the app directory. next-intl is adopting the new capabilities and is currently offering a beta version to early adopters, who are already building apps with the app directory.

⚠️

The app directory is currently in beta, patterns are still emerging and APIs may change. Please use this at your own risk, knowing that you might have to face a migration effort when the app directory becomes stable.

Current beta version

npm install next-intl@2.12.0-beta.2

This beta version was tested with next@13.2.0.

Roadmap

✅ All APIs from next-intl can be used in Server Components.
💡 Currently SSR-only (i.e. no generateStaticParams), therefore use CDN caching.

For details, see the pending pull request for Server Components support (opens in a new tab).

Getting started

If you haven't done so already, create a Next.js 13 app that uses the app directory (opens in a new tab). All pages should be moved within a [locale] folder so that we can use this segment to provide content in different languages (e.g. /en, /en/about, etc.).

Start by creating the following file structure:

├── messages (1)
│   ├── en.json
│   └── ...
├── i18n.ts (2)
├── next.config.js (3)
├── middleware.ts (4)
└── app
    └── [locale]
        ├── layout.tsx (5)
        └── page.tsx (6)

Now, set up the files as follows:

`messages/en.json`

Messages can be provided locally or loaded from a remote data source (e.g. a translation management system). Use whatever suits your workflow best.

The simplest option is to create JSON files locally based on locales, e.g. en.json.

messages/en.json

{
  "Index": {
    "title": "Hello world!"
  }
}

`i18n.ts`

next-intl creates a configuration once per request and makes it available to all Server Components. Here you can provide messages depending the locale of the user.

i18n.ts

import {getRequestConfig} from 'next-intl/server';
 
export default getRequestConfig(async ({locale}) => ({
  messages: (await import(`./messages/${locale}.json`)).default
}));

`next.config.js`

Now, set up the plugin and provide the path to your configuration.

next.config.js

const withNextIntl = require('next-intl/plugin')(
  // This is the default (also the `src` folder is supported out of the box)
  './i18n.ts'
);
 
module.exports = withNextIntl({
  // Other Next.js configuration ...
  experimental: {appDir: true}
});

`middleware.ts`

The middleware matches a locale for the request and handles redirects and rewrites accordingly.

middleware.ts

import createIntlMiddleware from 'next-intl/middleware';
 
export default createIntlMiddleware({
  // A list of all locales that are supported
  locales: ['en', 'de'],
 
  // If this locale is matched, pathnames work without a prefix (e.g. `/about`)
  defaultLocale: 'en'
});
 
export const config = {
  // Skip all paths that aren't pages that you'd like to internationalize
  matcher: ['/((?!api|_next|favicon.ico|assets).*)']
};

`app/[locale]/layout.tsx`

The locale that was matched by the middleware is available via useLocale and can be used to configure the document language.

app/[locale]/layout.tsx

import {useLocale} from 'next-intl';
import {notFound} from 'next/navigation';
 
export default function LocaleLayout({children, params}) {
  const locale = useLocale();
 
  // Show a 404 error if the user requests an unknown locale
  if (params.locale !== locale) {
    notFound();
  }
 
  return (
    <html lang={locale}>
      <body>{children}</body>
    </html>
  );
}

`app/[locale]/page.tsx`

Use translations in your page components or anywhere else!

app/[locale]/page.tsx

import {useTranslations} from 'next-intl';
 
export default function Index() {
  const t = useTranslations('Index');
  return <h1>{t('title')}</h1>;
}

That's all it takes! Now you can internationalize your apps on the server side.

If you've encountered an issue, you can explore the code for a working example (opens in a new tab) (demo (opens in a new tab)).

If you're in a transitioning phase, either from the pages directory to the app directory, or from Client Components to the Server Components beta, you can apply NextIntlClientProvider additionally.

Routing

`Link`

next-intl provides a drop-in replacement for next/link that will automatically prefix the href with the current locale as necessary. If the default locale is matched, the href remains unchanged and no prefix is added.

import {Link} from 'next-intl';
 
// When the user is on `/en`, the link will point to `/en/about`
<Link href="/about">About</Link>
 
// You can override the `locale` to switch to another language
<Link href="/" locale="de">Switch to German</Link>

`useRouter`

If you need to navigate programmatically (e.g. in response to a form submission), next-intl provides a convience API that wraps useRouter from Next.js and automatically applies the locale of the user.

'use client';
 
import {useRouter} from 'next-intl/client';
 
const router = useRouter();
 
// When the user is on `/en`, the router will navigate to `/en/about`
router.push('/about');

`usePathname`

To retrieve the pathname without a potential locale prefix, you can call usePathname.

'use client';
 
import {usePathname} from 'next-intl/client';
 
// When the user is on `/en`, this will be `/`
const pathname = usePathname();

`redirect`

If you want to interrupt the render of a Server Component and redirect to another page, you can invoke the redirect function from next-intl. This wraps the redirect function from Next.js (opens in a new tab) and automatically applies the current locale.

import {redirect} from 'next-intl/server';
 
export default async function Profile() {
  const user = await fetchUser();
 
  if (!user) {
    // When the user is on `/en/profile`, this will be `/en/login`
    redirect('/login');
  }
 
  // ...
}

Switching to Client Components

If you need to use translations in Client Components, the best approach is to pass the generated labels as props.

[locale]/faq/page.tsx

import {useTranslations} from 'next-intl';
import Expandable from './Expandable';
 
export default function FAQ() {
  const t = useTranslations('FAQ');
  return <Expandable title={t('title')}>{t('description')}</Expandable>;
}

Expandable.tsx

'use client';
 
import {useState} from 'react';
 
function Expandable({title, children}) {
  const [expanded, setExpanded] = useState(false);
 
  function onToggle() {
    setExpanded(!expanded);
  }
 
  return (
    <div>
      <button onClick={onToggle}>{title}</button>
      {expanded && <p>{children}</p>}
    </div>
  );
}

This way your messages never leave the server and the client only needs to load the code that is necessary for initializing your interactive components.

If you absolutely need to use functionality from next-intl on the client side, you can wrap the respective components with NextIntlClientProvider (example code (opens in a new tab)). Note however that this will increase your client bundle size.

Global request configuration

If you'd like to apply global configuration like formats, defaultTranslationValues, timeZone, now, or error handling functions like onError and getMessageFallback, you can provide these in i18n.ts.

i18n.ts

import {headers} from 'next/headers';
import {getRequestConfig} from 'next-intl/server';
 
export default getRequestConfig(async ({locale}) => ({
  messages: (await import(`../messages/${locale}.json`)).default,
 
  // You can read from headers or cookies here if necessary
  timeZone: headers().get('x-time-zone') ?? 'Europe/Berlin'
}));

Middleware configuration

The middleware handles redirects and rewrites based on the detected user locale.

Routing with a locale prefix (default)

By default, next-intl will map the incoming requests to your defined routes (e.g. /de/about matches [locale]/about/page.tsx). To keep the URL short, requests for the default locale are rewritten internally to work without a locale prefix (e.g. /about matches [locale]/about/page.tsx too).

When the user visits a route without an explicit locale, next-intl matches the accept-language header (opens in a new tab) of the request against the available locales and optionally redirects the user to a prefixed route. Note that a previously matched locale is saved in a cookie for subsequent requests.

If you want to include a prefix for the default locale as well, you can configure the middleware accordingly.

import createIntlMiddleware from 'next-intl/middleware';
 
export default createIntlMiddleware({
  locales: ['en', 'de'],
  defaultLocale: 'en',
 
  routing: {
    type: 'prefix',
    prefix: 'always' // Default: 'as-needed'
  }
});

Routing with domains

If you want to serve your localized content based on separate domains, you can provide a list of mappings between domains and locales to the middleware.

import createIntlMiddleware from 'next-intl/middleware';
 
export default createIntlMiddleware({
  locales: ['en', 'de'],
  defaultLocale: 'en',
 
  routing: {
    type: 'domain',
    domains: [
      {
        domain: 'en.example.com',
        locale: 'en'
      },
      {
        domain: 'de.example.com',
        locale: 'de'
      }
    ]
  }
});

In this case, your content will be available without a locale prefix based on the domain since next-intl rewrites the request internally (e.g. de.example.com/about matches [locales]/about/page.tsx).

The domain that is needed to match the locale is read from the x-forwarded-host header, with a fallback to the host header. If no domain matches (e.g. on localhost), the defaultLocale is used.

Alternate links

next-intl automatically sets the link header (opens in a new tab) to inform search engines that your content is available in different languages.

If you prefer to include these links yourself, you can opt-out of this behaviour.

middleware.ts

import createIntlMiddleware from 'next-intl/middleware';
 
export default createIntlMiddleware({
  // ... other config
 
  // Default: `true`
  alternateLinks: false
});

Localizing pathnames

If you want to localize the pathnames of your app, you can accomplish this by using appropriate rewrites (opens in a new tab).

next.config.js

const withNextIntl = require('next-intl/plugin')();
 
module.exports = withNextIntl({
  experimental: {appDir: true},
  rewrites() {
    return [
      {
        source: '/de/über',
        destination: '/de/about'
      }
    ];
  }
});

Since next-intl isn't aware of the rewrites you've configured, you likely want to make some adjustments:

Turn off the alternateLinks option in the middleware and provide search engine hints about localized versions of your content (opens in a new tab) by yourself.
Translate the pathnames you're passing to the routing APIs from next-intl (example (opens in a new tab)).

Using internationalization outside of components

If you need to use translated messages in functions like generateMetadata, you can import awaitable versions of the functions that you usually call as hooks from next-intl/server.

app/[locale]/layout.tsx

import {getTranslations} from 'next-intl/server';
 
export async function generateMetadata() {
  const t = await getTranslations('Metadata');
 
  return {
    title: t('title'),
    description: t('description')
  };
}

These functions are available from next-intl/server for usage outside of components:

import {
  getTranslations, // like `useTranslations`
  getFormatter, // like `useFormatter`
  getLocale, // like `useLocale`
  getNow, // like `useNow`
  getTimeZone // like `useTimeZone`
} from 'next-intl/server';

CDN caching

Since next-intl is currently SSR-only, it's a good idea to use CDN caching (opens in a new tab) via headers (opens in a new tab) in next.config.js to get the same level of performance from SSR'd pages (learn more (opens in a new tab)).

next.config.js

const ms = require('ms');
const withNextIntl = require('next-intl/plugin')();
 
module.exports = withNextIntl({
  // ... Other config
 
  headers() {
    return [
      {
        // Cache all content pages
        source: '/((?!_next|assets|favicon.ico).*)',
        headers: [
          {
            key: 'Cache-Control',
            value: [
              `s-maxage=` + ms('1d') / 1000,
              `stale-while-revalidate=` + ms('1y') / 1000
            ].join(', ')
          }
        ],
 
        // If you're deploying on a host that doesn't support the `vary` header (e.g. Vercel),
        // make sure to disable caching for prefetch requests for Server Components.
        missing: [
          {
            type: 'header',
            key: 'Next-Router-Prefetch'
          }
        ]
      }
    ];
  }
});

Providing feedback

If you have feedback about using next-intl in the app directory, feel free to leave feedback in the PR which implements the React Server Components support (opens in a new tab).

Client Components