Add i18n features - Withastro

import { FileTree } from '@astrojs/starlight/components'; import ReadMore from '~~/components/ReadMore.astro'; import { Steps } from '@astrojs/starlight/components'; import StaticSsrTabs from '~~/components/tabs/StaticSsrTabs.astro';

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.

<ReadMore>See the resources section for external links to related topics such as right-to-left (RTL) styling and choosing language tags.</ReadMore>

Recipe

Set up pages for each language

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

<FileTree>
- src/
  - pages/
    - **en/**
      - about.astro
      - index.astro
    - **fr/**
      - about.astro
      - index.astro
    - index.astro
</FileTree>

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

<StaticSsrTabs>
  <Fragment slot="static">
    ```astro
    ---
    // src/pages/index.astro
    ---
    <meta http-equiv="refresh" content="0;url=/en/" />
    ```

    This approach uses a [meta refresh](https://en.wikipedia.org/wiki/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.
  </Fragment>
  
  <Fragment slot="ssr">
    If you are using an SSR adapter, you can use [`Astro.redirect`](/en/guides/routing/#dynamic-redirects) to redirect to the default language on the server.

    ```astro
    ---
    // src/pages/index.astro
    return Astro.redirect('/en/');
    ---
    ```
  </Fragment>
</StaticSsrTabs>

</Steps>

Use collections for translated content

<Steps> 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:

<FileTree>
- src/
  - content/
      - blog/
        - **en/** Blog posts in English
            - post-1.md
            - post-2.md
        - **fr/** Blog posts in French
          - post-1.md
          - post-2.md
</FileTree>

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

```ts
//src/content.config.ts
import { defineCollection } from 'astro:content';
import { z } from 'astro/zod';

const blogCollection = defineCollection({
  schema: z.object({
    title: z.string(),
    author: z.string(),
    date: z.date()
  })
});

export const collections = {
  'blog': blogCollection
};

```

<ReadMore>Read more about [Content Collections](/en/guides/content-collections/).</ReadMore>

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

<StaticSsrTabs>
  <Fragment slot="static">
    In static rendering mode, use `getStaticPaths` to map each content entry to a page:

    ```astro
    //src/pages/[lang]/blog/[...slug].astro
    ---
    import { getCollection, render } from 'astro:content';
    
    export async function getStaticPaths() {
      const pages = await getCollection('blog');

      const paths = pages.map(page => {
        const [lang, ...slug] = page.id.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 render(page);
    ---
    <h1>{page.data.title}</h1>
    <p>by {page.data.author} • {formattedDate}</p>
    <Content/>
    ```
  </Fragment>

  <Fragment slot="ssr">
    In [SSR mode](/en/guides/on-demand-rendering/), fetch the requested entry directly:

    ```astro
    //src/pages/[lang]/blog/[...slug].astro
    ---
    import { getEntry, render } from 'astro:content';

    const { lang, slug } = Astro.params;
    const page = await getEntry('blog', `${lang}/${slug}`);

    if (!page) {
      return Astro.redirect('/404');
    }

    const formattedDate = page.data.date.toLocaleString(lang);
    const { Content, headings } = await render(page);
    ---
    <h1>{page.data.title}</h1>
    <p>by {page.data.author} • {formattedDate}</p>
    <Content/>
    ```
  </Fragment>
</StaticSsrTabs>

<ReadMore>Read more about [dynamic routing](/en/guides/routing/#dynamic-routes).</ReadMore>

:::tip[Date formatting]
The example above uses the built-in [`toLocaleString()` date-formatting method](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleString) to create a human-readable string from the frontmatter date.
This ensures the date and time are formatted to match the user’s language.
:::

</Steps>

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.

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

```ts
// 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:

```js
// 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];
  }
}
```

:::note[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:

```astro 
---
// 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:

```astro
---
// 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.

```astro
---
// src/pages/en/about.astro
import Base from '../../layouts/Base.astro';
---
<Base>
    <h1>About me</h1>
    ...
</Base>
```

</Steps>

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.

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

```astro
---
// 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:

```astro ins={3,17-19}
---
// 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>
```

</Steps>

Hide default language in the URL

<Steps> 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/`:

<FileTree>
- src/
  - pages/
    - about.astro
    - index.astro
    - **fr/**
      - about.astro
      - index.astro
</FileTree>

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

```ts
// 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}`
  }
}

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

astro

---
// 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>

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

astro

---
// src/components/LanguagePicker.astro
import { languages } from '../i18n/ui';
import { getLangFromUrl, useTranslatedPath } from '../i18n/utils';

const lang = getLangFromUrl(Astro.url);
const translatePath = useTranslatedPath(lang);
---
<ul>
  {Object.entries(languages).map(([lang, label]) => (
    <li>
      <a href={translatePath('/', lang)}>{label}</a>
    </li>
  ))}
</ul>

</Steps>

Translate Routes

Translate the routes of your pages for each language.

<Steps> 1. Add route mappings to `src/i18n/ui.ts`:

```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.

```js
// 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:

```js
// 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:

```astro
---
// src/components/LanguagePicker.astro
import { languages } from '../i18n/ui';
import { getRouteFromUrl, useTranslatedPath } from '../i18n/utils';

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

</Steps>

Resources

Community libraries

Find community-built i18n utilities that you can add to your Astro project in our integrations directory.