Skip to content
DocsRouting

Routing

💡

Routing APIs are only needed when you’re using i18n routing.

next-intl integrates with the routing system of Next.js in two places:

  1. Middleware: Negotiates the locale and handles redirects & rewrites (e.g. //en)
  2. Navigation APIs: Lightweight wrappers around Next.js’ navigation APIs like <Link />

This enables you to express your app in terms of APIs like <Link href="/about">, while aspects like the locale and user-facing pathnames are automatically handled behind the scenes (e.g. /de/ueber-uns).

defineRouting

The routing configuration that is shared between the middleware and the navigation APIs can be defined with the defineRouting function.

src/i18n/routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // A list of all locales that are supported
  locales: ['en', 'de'],
 
  // Used when no locale matches
  defaultLocale: 'en'
});

Depending on your routing needs, you may wish to consider further settings—see below.

What if the locales aren’t known at build time?

In case you’re building an app where locales can be added and removed at runtime, you can provide the routing configuration for the middleware dynamically per request.

To create the corresponding navigation APIs, you can omit the locales argument from createNavigation in this case.

Still, in case you’re defining other routing config, make sure to keep them in sync between the middleware and the navigation APIs.

localePrefix

By default, the pathnames of your app will be available under a prefix that matches your directory structure (e.g. /en/aboutapp/[locale]/about/page.tsx). You can however adapt the routing to optionally remove the prefix or customize it per locale by configuring the localePrefix setting.

localePrefix: 'always' (default)

By default, pathnames always start with the locale (e.g. /en/about).

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // ...
  localePrefix: 'always'
});

localePrefix: 'as-needed'

If you want to use no prefix for the default locale (e.g. /about) while keeping it for other locales (e.g. /de/about), you can configure your routing accordingly:

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // ...
  localePrefix: 'as-needed'
});

Note that:

  1. If you use this routing strategy, make sure that your middleware matcher detects unprefixed pathnames.
  2. The middleware will by default set a cookie to remember the user’s locale preference. If no explicit locale prefix is present in the pathname, then locale detection will potentially redirect users to the latest locale that was matched based on the cookie value (e.g. //de).
  3. If a superfluous locale prefix like /en/about is requested, the middleware will automatically redirect to the unprefixed version /about. This can be helpful in case you’re redirecting from another locale and you want to update a potential cookie value first (e.g. <Link /> relies on this mechanism).

localePrefix: 'never'

If you’d like to provide a locale to next-intl, e.g. based on user settings, you can consider setting up next-intl without i18n routing. This way, you don’t need to use the routing integration in the first place.

However, you can also configure the middleware to never show a locale prefix in the URL, which can be helpful in the following cases:

  1. You want to use domain-based routing and have only one locale per domain
  2. You want to use a cookie to determine the locale while enabling static rendering
routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // ...
  localePrefix: 'never'
});

In this case, requests for all locales will be rewritten to have the locale only prefixed internally. You still need to place all your pages inside a [locale] folder for the routes to be able to receive the locale param.

Note that:

  1. If you use this routing strategy, make sure that your middleware matcher detects unprefixed pathnames.
  2. Alternate links are disabled in this mode since URLs might not be unique per locale. Due to this, consider including these yourself, or set up a sitemap that links localized pages via alternates.
  3. You can consider increasing the maxAge attribute of the locale cookie to a longer duration to remember the user’s preference across sessions.

prefixes

If you’d like to customize the user-facing prefix, you can provide a locale-based mapping:

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  locales: ['en-US', 'de-AT', 'zh'],
  defaultLocale: 'en-US',
  localePrefix: {
    mode: 'always',
    prefixes: {
      'en-US': '/us',
      'de-AT': '/eu/at'
      // (/zh will be used as-is)
    }
  }
});

Note that:

  1. You should adapt your middleware matcher to match the custom prefixes.
  2. Custom prefixes are only visible to the user and rewritten internally to the corresponding locale. Therefore, the [locale] segment corresponds to the locale, not the prefix.
Can I read the matched prefix in my app?

Since the custom prefix is rewritten to the locale internally, you can’t access the prefix directly. However, you can extract details like the region from the locale:

import {useLocale} from 'next-intl';
 
function Component() {
  // Assuming the locale is 'en-US'
  const locale = useLocale();
 
  // Extracts the "US" region
  const {region} = new Intl.Locale(locale);
}

The region must be a valid ISO 3166-1 alpha-2 country code or a UN M49 region code. When passed to Intl.Locale, the region code is treated as case-insensitive and normalized to uppercase. You can also combine languages with regions where the language is not natively spoken (e.g. en-AT describes English as used in Austria).

Apart from the region, a locale can encode further properties, like the numbering system.

If you’d like to encode custom information in the locale, you can use arbitrary private extensions, denoted by the -x- prefix (e.g. en-US-x-usd). The Intl.Locale constructor ignores private extensions, but you can extract them from the locale string manually.

pathnames

Many apps choose to localize pathnames, especially when search engine optimization is relevant.

Example:

  • /en/about
  • /de/ueber-uns

Since you typically want to define these routes only once internally, you can use the next-intl middleware to rewrite such incoming requests to shared pathnames.

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  locales: ['en-US', 'en-UK', 'de'],
  defaultLocale: 'en-US',
 
  // The `pathnames` object holds pairs of internal and
  // external paths. Based on the locale, the external
  // paths are rewritten to the shared, internal ones.
  pathnames: {
    // If all locales use the same pathname, a single
    // external path can be used for all locales
    '/': '/',
    '/blog': '/blog',
 
    // If some locales use different paths, you can
    // specify the relevant external pathnames
    '/about': {
      de: '/ueber-uns'
    },
 
    // Dynamic params are supported via square brackets
    '/news/[articleSlug]': {
      de: '/neuigkeiten/[articleSlug]'
    },
 
    // Static pathnames that overlap with dynamic segments
    // will be prioritized over the dynamic segment
    '/news/just-in': {
      de: '/neuigkeiten/aktuell'
    },
 
    // Also (optional) catch-all segments are supported
    '/categories/[...slug]': {
      de: '/kategorien/[...slug]'
    }
  }
});

Localized pathnames map to a single internal pathname that is created via the file-system based routing in Next.js. In the example above, /de/ueber-uns will be handled by the page at /[locale]/about/page.tsx.

How can I revalidate localized pathnames?

Depending on if a route is generated statically (at build time) or dynamically (at runtime), revalidatePath needs to be called either for the localized or the internal pathname.

Consider this example:

app
└── [locale]
    └── news
        └── [slug]

… with this routing configuration:

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  locales: ['en', 'de'],
  defaultLocale: 'en',
  pathnames: {
    '/news/[slug]': {
      en: '/news/[slug]',
      de: '/neuigkeiten/[slug]'
    }
  }
});

Depending on whether some-article was included in generateStaticParams or not, you can revalidate the route like this:

// Statically generated at build time
revalidatePath('/de/news/some-article');
 
// Dynamically generated at runtime:
revalidatePath('/de/neuigkeiten/some-article');

When in doubt, you can revalidate with revalidateTag instead.

See also: vercel/next.js#59825

How can I localize dynamic segments?

If you have a route like /news/[articleSlug]-[articleId], you may want to localize the articleSlug part in the pathname like this:

/en/news/launch-of-new-product-94812
/de/neuigkeiten/produktneuheit-94812

In this case, the localized slug can either be provided by the backend or generated in the frontend by slugifying the localized article title.

A good practice is to include the ID in the URL, allowing you to retrieve the article based on this information from the backend. The ID can be further used to implement self-healing URLs, where a redirect is added if the articleSlug doesn’t match.

If you localize the values for dynamic segments, you might want to turn off alternate links and provide your own implementation that considers localized values for dynamic segments.

How do I integrate with an external system like a CMS that provides localized pathnames?

In case you’re using a system like a CMS to configure localized pathnames, you’ll typically implement this with a dynamic segment that catches all localized pathnames instead of using the pathnames configuration from next-intl.

Examples:

  1. All pathnames are handled by your CMS: [locale]/[[...slug]]/page.tsx
  2. Some pathnames are handled by your CMS: [locale]/blog/[...slug]/page.tsx
page.tsx
import {notFound} from 'next';
import {Locale} from 'next-intl';
import {fetchContent} from './cms';
 
type Props = {
  params: Promise<{
    locale: Locale;
    slug: Array<string>;
  }>;
};
 
export default async function CatchAllPage({params}: Props) {
  const {locale, slug} = await params;
  const content = await fetchContent(locale, slug);
  if (!content) notFound();
 
  // ...
}

In this case, you’ll likely want to disable alternate links and provide your own implementation instead.

Furthermore, in case you provide a locale switcher, it might require special care to be able to switch between localized pathnames of the same page. A simplified implementation might always redirect to the home page instead.

domains

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

Examples:

  • us.example.com: en-US
  • ca.example.com: en-CA
  • ca.example.com/fr: fr-CA
  • fr.example.com: fr-FR

In many cases, domains are combined with a localePrefix setting to achieve results as shown above. Also custom prefixes can be used to customize the user-facing prefix per locale.

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  locales: ['en-US', 'en-CA', 'fr-CA', 'fr-FR'],
  defaultLocale: 'en-US',
  domains: [
    {
      domain: 'us.example.com',
      defaultLocale: 'en-US',
      locales: ['en-US']
    },
    {
      domain: 'ca.example.com',
      defaultLocale: 'en-CA',
      locales: ['en-CA', 'fr-CA']
    },
    {
      domain: 'fr.example.com',
      defaultLocale: 'fr-FR',
      locales: ['fr-FR']
    }
  ],
  localePrefix: {
    mode: 'as-needed',
    prefixes: {
      // Cleaner prefix for `ca.example.com/fr`
      'fr-CA': '/fr'
    }
  }
});

Locales are required to be unique across domains, therefore regional variants are typically used to avoid conflicts. Note however that you don’t necessarily need to provide messages for each locale if the overall language is sufficient for your use case.

If no domain matches, the middleware will fall back to the general defaultLocale (e.g. on localhost).

How can I locally test if my setup is working?

To test your domain setup locally, you can conditionally adapt the domains to refer to hosts that are available locally:

routing.ts
import {defineRouting} from 'next-intl/routing';
 
const isDev = process.env.NODE_ENV === 'development';
 
export const routing = defineConfig({
  // ...
  domains: [
    {
      domain: isDev ? 'localhost:3000' : 'us.example.com'
      // ...
    },
    {
      domain: isDev ? 'localhost:3001' : 'ca.example.com'
      // ...
    }
  ]
});

Now, you can run your development server on one of the configured ports and test the routing for different use cases:

# Like `us.example.com`
PORT=3000 npm run dev
 
# Like `ca.example.com`
PORT=3001 npm run dev
Can I use a different localePrefix setting per domain?

While this is currently not supported out of the box, you can still achieve this by building the app for each domain separately while injecting diverging routing configuration via an environment variable.

Example:

routing.ts
import {defineRouting} from 'next-intl/routing';
 
const isUsDomain =
  process.env.VERCEL_PROJECT_PRODUCTION_URL === 'us.example.com';
 
export const routing = defineRouting({
  locales: isUsDomain ? ['en-US'] : ['en-CA', 'fr-CA'],
  defaultLocale: isUsDomain ? 'en-US' : 'en-CA',
  localePrefix: isUsDomain ? 'never' : 'always'
});

localeDetection

The middleware will detect a matching locale based on your routing configuration & the incoming request and will either pass the request through for a matching locale or redirect to one that matches.

If you want to rely entirely on the URL to resolve the locale, you can set the localeDetection property to false. This will disable locale detection based on the accept-language header and a potentially existing cookie value from a previous visit.

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // ...
  localeDetection: false
});

In this case, only the locale prefix and a potentially matching domain are used to determine the locale.

If a user changes the locale to a value that doesn’t match the accept-language header, next-intl will set a session cookie called NEXT_LOCALE that contains the most recently detected locale. This is used to remember the user’s locale preference for subsequent requests.

By default, the cookie will be configured with the following attributes:

  1. sameSite: This value is set to lax so that the cookie can be set when coming from an external site.
  2. path: This value is not set by default, but will use the value of your basePath if configured.

If you have more specific requirements, you can adjust these settings accordingly:

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // ...
 
  // Will be merged with the defaults
  localeCookie: {
    // Custom cookie name
    name: 'USER_LOCALE',
    // Expire in one year
    maxAge: 60 * 60 * 24 * 365
  }
});

… or turn the cookie off entirely:

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // ...
 
  localeCookie: false
});

The middleware automatically sets the link header to inform search engines that your content is available in different languages. Note that this automatically integrates with your routing strategy and will generate the correct links based on your configuration.

However, there are cases where you may want to provide these links yourself:

  1. You have pages that are only available for certain locales
  2. You’re using an external system like a CMS to manage localized slugs of your pages

In this case, you can opt-out of this behavior by setting alternateLinks to false.

routing.ts
import {defineRouting} from 'next-intl/routing';
 
export const routing = defineRouting({
  // ...
 
  alternateLinks: false
});

If you decide to manage alternate links yourself, a good option can be to include them in a sitemap.

next.config.ts

Apart from your routing configuration, next-intl will also incorporate settings from next.config.ts.

basePath

The next-intl middleware as well as the navigation APIs will automatically pick up a basePath that you might have configured in your next.config.js.

Note however that you should make sure that your middleware matcher handles the root of your base path:

middleware.ts
export const config = {
  // The `matcher` is relative to the `basePath`
  matcher: [
    // This entry handles the root of the base
    // path and should always be included
    '/'
 
    // ... other matcher config
  ]
};

trailingSlash

If you have trailingSlash set to true in your Next.js config, this setting will be taken into account by the middleware and the navigation APIs.

Note that if you’re using pathnames, your internal and external pathnames can be defined either with or without a trailing slash as they will be normalized internally.

Docs

 · 

Examples

 · 

Blog

 ·