Add i18n features

In this recipe, you will learn how to use content collections and dynamic routing to build your own internationalization (i18n) solution and serve your content in different languages.

Tip

In v4.0, Astro added built-in support for i18n routing that allows you to configure default and supported languages and includes valuable helper functions to assist you in serving an international audience. If you want to use this instead, see our internationalization guide to learn about these features.

This example serves each language at its own subpath, e.g. example.com/en/blog for English and example.com/fr/blog for French.

If you prefer the default language to not be visible in the URL unlike other languages, there are instructions to hide the default language below.

Recipe

Section titled Recipe

Set up pages for each language

Section titled Set up pages for each language

1. Create a directory for each language you want to support. For example, en/ and fr/ if you are supporting English and French:

   • Verzeichnissrc/

     • Verzeichnispages/

       • Verzeichnisen/

         • about.astro
         • index.astro
       • Verzeichnisfr/

         • about.astro
         • index.astro
       • index.astro

2. Set up src/pages/index.astro to redirect to your default language.

   Static

   src/pages/index.astro

   <meta http-equiv="refresh" content="0;url=/en/" />

   This approach uses a meta refresh and will work however you deploy your site. Some static hosts also let you configure server redirects with a custom configuration file. See your deploy platform’s documentation for more details.

   SSR

   If you are using an SSR adapter, you can use Astro.redirect to redirect to the default language on the server.

   src/pages/index.astro

   ---
   return Astro.redirect('/en/');
   ---

Use collections for translated content

Section titled Use collections for translated content

1. Create a folder in src/content/ for each type of content you want to include and add subdirectories for each supported language. For example, to support English and French blog posts:

   • Verzeichnissrc/

     • Verzeichniscontent/

       • Verzeichnisblog/

         • Verzeichnisen/ Blog posts in English

           • post-1.md
           • post-2.md
         • Verzeichnisfr/ Blog posts in French

           • post-1.md
           • post-2.md

2. Create a src/content/config.ts file and export a collection for each type of content.

   src/content/config.ts

   import { defineCollection, z } from 'astro:content';
   
   const blogCollection = defineCollection({
     schema: z.object({
       title: z.string(),
       author: z.string(),
       date: z.date()
     })
   });
   
   export const collections = {
     'blog': blogCollection
   };

   📚 Read more about Content Collections.

3. Use dynamic routes to fetch and render content based on a lang and a slug parameter.

   Static

   In static rendering mode, use getStaticPaths to map each content entry to a page:

   src/pages/[lang]/blog/[...slug].astro

   ---
   import { getCollection } from 'astro:content'
   
   export async function getStaticPaths() {
     const pages = await getCollection('blog')
   
     const paths = pages.map(page => {
       const [lang, ...slug] = page.slug.split('/');
       return { params: { lang, slug: slug.join('/') || undefined }, props: page }
     })
   
     return paths;
   }
   
   const { lang, slug } = Astro.params;
   const page = Astro.props;
   const formattedDate = page.data.date.toLocaleString(lang);
   
   const { Content } = await page.render();
   ---
   <h1>{page.data.title}</h1>
   <p>by {page.data.author} • {formattedDate}</p>
   <Content/>

   SSR

   In SSR mode, fetch the requested entry directly:

   src/pages/[lang]/blog/[...slug].astro

   ---
   import { getEntryBySlug } from 'astro:content';
   
   const { lang, slug } = Astro.params;
   const page = await getEntryBySlug('blog', `${lang}/${slug}`);
   
   if (!page) {
     return Astro.redirect('/404');
   }
   
   const formattedDate = page.data.date.toLocaleString(lang);
   const { Content, headings } = await page.render();
   ---
   <h1>{page.data.title}</h1>
   <p>by {page.data.author} • {formattedDate}</p>
   <Content/>

   📚 Read more about dynamic routing.

   Date formatting

   The example above uses the built-in toLocaleString() date-formatting method to create a human-readable string from the frontmatter date. This ensures the date and time are formatted to match the user’s language.

Translate UI strings

Section titled Translate UI strings

Create dictionaries of terms to translate the labels for UI elements around your site. This allows your visitors to experience your site fully in their language.

1. Create a src/i18n/ui.ts file to store your translation strings:

   src/i18n/ui.ts

   export const languages = {
     en: 'English',
     fr: 'Français',
   };
   
   export const defaultLang = 'en';
   
   export const ui = {
     en: {
       'nav.home': 'Home',
       'nav.about': 'About',
       'nav.twitter': 'Twitter',
     },
     fr: {
       'nav.home': 'Accueil',
       'nav.about': 'À propos',
     },
   } as const;

2. Create two helper functions: one to detect the page language based on the current URL, and one to get translations strings for different parts of the UI in src/i18n/utils.ts:

   src/i18n/utils.ts

   import { ui, defaultLang } from './ui';
   
   export function getLangFromUrl(url: URL) {
     const [, lang] = url.pathname.split('/');
     if (lang in ui) return lang as keyof typeof ui;
     return defaultLang;
   }
   
   export function useTranslations(lang: keyof typeof ui) {
     return function t(key: keyof typeof ui[typeof defaultLang]) {
       return ui[lang][key] || ui[defaultLang][key];
     }
   }

   Did you notice?

   In step 1, the nav.twitter string was not translated to French. You may not want every term translated, such as proper names or common industry terms. The useTranslations helper will return the default language’s value if a key is not translated. In this example, French users will also see “Twitter” in the nav bar.

3. Import the helpers where needed and use them to choose the UI string that corresponds to the current language. For example, a nav component might look like:

   src/components/Nav.astro

   ---
   import { getLangFromUrl, useTranslations } from '../i18n/utils';
   
   const lang = getLangFromUrl(Astro.url);
   const t = useTranslations(lang);
   ---
   <ul>
       <li>
           <a href={`/${lang}/home/`}>
             {t('nav.home')}
           </a>
       </li>
       <li>
           <a href={`/${lang}/about/`}>
             {t('nav.about')}
           </a>
       </li>
       <li>
           <a href="https://twitter.com/astrodotbuild">
             {t('nav.twitter')}
           </a>
       </li>
   </ul>

4. Each page must have a lang attribute on the <html> element that matches the language on the page. In this example, a reusable layout extracts the language from the current route:

   src/layouts/Base.astro

   ---
   import { getLangFromUrl } from '../i18n/utils';
   
   const lang = getLangFromUrl(Astro.url);
   ---
   <html lang={lang}>
       <head>
           <meta charset="utf-8" />
           <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
           <meta name="viewport" content="width=device-width" />
           <title>Astro</title>
       </head>
       <body>
           <slot />
       </body>
   </html>

   You can then use this base layout to ensure that pages use the correct lang attribute automatically.

   src/pages/en/about.astro

   ---
   import Base from "../../layouts/Base.astro"
   ---
   <Base>
       <h1>About me</h1>
       ...
   </Base>

Let users switch between languages

Section titled Let users switch between languages

Create links to the different languages you support so users can choose the language they want to read your site in.

1. Create a component to show a link for each language:

   src/components/LanguagePicker.astro

   ---
   import { languages } from '../i18n/ui';
   ---
   <ul>
     {Object.entries(languages).map(([lang, label]) => (
       <li>
         <a href={`/${lang}/`}>{label}</a>
       </li>
     ))}
   </ul>

2. Add <LanguagePicker /> to your site so it is shown on every page. The example below adds it to the site footer in a base layout:

   src/layouts/Base.astro

   ---
   import LanguagePicker from '../components/LanguagePicker.astro';
   import { getLangFromUrl } from '../i18n/utils';
   
   const lang = getLangFromUrl(Astro.url);
   ---
   <html lang={lang}>
       <head>
           <meta charset="utf-8" />
           <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
           <meta name="viewport" content="width=device-width" />
           <title>Astro</title>
       </head>
       <body>
           <slot />
           <footer>
             <LanguagePicker />
           </footer>
       </body>
   </html>

Hide default language in the URL

Section titled Hide default language in the URL

1. Create a directory for each language except the default language. For example, store your default language pages directly in pages/, and your translated pages in fr/:

   • Verzeichnissrc/

     • Verzeichnispages/

       • about.astro
       • index.astro
       • Verzeichnisfr/

         • about.astro
         • index.astro

2. Add another line to the src/i18n/ui.ts file to toggle the feature:

   src/i18n/ui.ts

   export const showDefaultLang = false;

3. Add a helper function to src/i18n/utils.ts, to translate paths based on the current language:

   src/i18n/utils.ts

    import { ui, defaultLang, showDefaultLang } from './ui';
   
    export function useTranslatedPath(lang: keyof typeof ui) {
      return function translatePath(path: string, l: string = lang) {
        return !showDefaultLang && l === defaultLang ? path : `/${l}${path}`
      }
    }

4. Import the helper where needed. For example, a nav component might look like:

   src/components/Nav.astro

   ---
   import { getLangFromUrl, useTranslations, useTranslatedPath } from '../i18n/utils';
   
   const lang = getLangFromUrl(Astro.url);
   const t = useTranslations(lang);
   const translatePath = useTranslatedPath(lang);
   ---
   <ul>
       <li>
           <a href={translatePath('/home/')}>
             {t('nav.home')}
           </a>
       </li>
       <li>
           <a href={translatePath('/about/')}>
             {t('nav.about')}
           </a>
       </li>
       <li>
           <a href="https://twitter.com/astrodotbuild">
             {t('nav.twitter')}
           </a>
       </li>
   </ul>

5. The helper function can also be used to translate paths for a specific language. For example, when users switch between languages:

   src/components/LanguagePicker.astro

   ---
   import { languages } from '../i18n/ui';
   ---
   
   <ul>
     {Object.entries(languages).map(([lang, label]) => (
       <li>
         <a href={translatePath('/', lang)}>{label}</a>
       </li>
     ))}
   </ul>

Translate Routes

Section titled Translate Routes

Translate the routes of your pages for each language.

1. Add route mappings to src/i18n/ui.ts:

   src/i18n/ui.ts

   export const routes = {
     de: {
       'services': 'leistungen',
     },
     fr: {
       'services': 'prestations-de-service',
     },
     }

2. Update the useTranslatedPath helper function in src/i18n/utils.ts to add router translation logic.

   src/i18n/utils.ts

   import { ui, defaultLang, showDefaultLang, routes } from './ui';
   
   export function useTranslatedPath(lang: keyof typeof ui) {
     return function translatePath(path: string, l: string = lang) {
       const pathName = path.replaceAll('/', '')
       const hasTranslation = defaultLang !== l && routes[l] !== undefined && routes[l][pathName] !== undefined
       const translatedPath = hasTranslation ? '/' + routes[l][pathName] : path
   
       return !showDefaultLang && l === defaultLang ? translatedPath : `/${l}${translatedPath}`
     }
   }

3. Create a helper function to get the route, if it exists based on the current URL, in src/i18n/utils.ts:

   src/i18n/utils.ts

   import { ui, defaultLang, showDefaultLang, routes } from './ui';
   
   export function getRouteFromUrl(url: URL): string | undefined {
     const pathname = new URL(url).pathname
     const parts = pathname?.split('/')
     const path = parts.pop() || parts.pop()
   
     if (path === undefined) {
       return undefined
     }
   
     const currentLang = getLangFromUrl(url);
   
     if (defaultLang === currentLang) {
       const route = Object.values(routes)[0];
       return route[path] !== undefined ? route[path] : undefined
     }
   
     const getKeyByValue = (obj: Record<string, string>, value: string): string | undefined  => {
         return Object.keys(obj).find((key) => obj[key] === value)
     }
   
     const reversedKey = getKeyByValue(routes[currentLang], path)
   
     if (reversedKey !== undefined) {
       return reversedKey
     }
   
     return undefined
   }

4. The helper function can be used to get a translated route. For example, when no translated route is defined, the user will be redirected to the home page:

   src/components/LanguagePicker.astro

     ---
     import { languages } from '../i18n/ui';
     import { getRouteFromUrl } from '../i18n/utils';
     const route = getRouteFromUrl(Astro.url);
     ---
   
     <ul>
       {Object.entries(languages).map(([lang, label]) => (
         <li>
           <a href={translatePath(`/${route ? route : ''}`, lang)}>{label}</a>
         </li>
       ))}
     </ul>

Resources

Section titled Resources

• Choosing a Language Tag
• Right-to-left Styling 101

Community libraries

Section titled Community libraries

• astro-i18next — An Astro integration for i18next including some utility components.
• astro-i18n — A TypeScript-first internationalization library for Astro.
• astro-i18n-aut — An Astro integration for i18n that supports the defaultLocale without page generation. The integration is adapter agnostic and UI framework agnostic.