---
createdAt: 2026-04-24
updatedAt: 2026-05-06
title: Astro + Svelte i18n - How to translate an Astro + Svelte application in 2026
description: Learn how to add internationalisation (i18n) to your Astro + Svelte site with Intlayer. Follow this guide to make your site multilingual.
keywords:
  - internationalisation
  - documentation
  - Intlayer
  - Astro
  - Svelte
  - i18n
  - JavaScript
slugs:
  - doc
  - environment
  - astro
  - svelte
applicationTemplate: https://github.com/aymericzip/intlayer-astro-template
applicationShowcase: https://intlayer-astro-template.vercel.app
history:
  - version: 8.9.0
    date: 2026-05-04
    changes: "Update Solid useIntlayer API usage to direct property access"
  - version: 8.7.7
    date: 2026-04-24
    changes: "Initial documentation for Astro + Svelte"
---

# Translate your Astro + Svelte site with Intlayer | Internationalisation (i18n)

<Tabs defaultTab="code">
  <Tab label="Code" value="code">

<iframe
  src="https://ide.intlayer.org/aymericzip/intlayer-astro-template?file=intlayer.config.ts"
  className="m-auto overflow-hidden rounded-lg border-0 max-md:size-full max-md:h-[700px] md:aspect-16/9 md:w-full"
  title="Demo CodeSandbox - How to internationalise your application with Intlayer"
  sandbox="allow-forms allow-modals allow-popups allow-presentation allow-same-origin allow-scripts"
  loading="lazy"
/>

  </Tab>
  <Tab label="Demo" value="demo">

<iframe
  src="https://intlayer-astro-template.vercel.app"
  className="m-auto overflow-hidden rounded-lg border-0 max-md:size-full max-md:h-[700px] md:aspect-16/9 md:w-full"
  title="Demo - intlayer-astro-template"
  sandbox="allow-forms allow-modals allow-popups allow-presentation allow-same-origin allow-scripts"
  loading="lazy"
/>

  </Tab>
</Tabs>

## Table of Contents

<TOC/>

## What is Intlayer?

**Intlayer** is an innovative, open-source internationalisation (i18n) library designed to simplify multilingual support in modern web applications.

With Intlayer, you can:

- **Manage translations easily**: Using declarative dictionaries at the component level.
- **Localise metadata, routes and content dynamically**.
- **Ensure TypeScript support**: With autogenerated types for better autocompletion and error detection.
- **Benefit from advanced features**: Such as dynamic language detection and switching.

---

## Step-by-Step Guide to Configure Intlayer in Astro + Svelte

Check out the [application template](https://github.com/aymericzip/intlayer-astro-template) on GitHub.

### Step 1: Install Dependencies

Install the necessary packages using your preferred package manager:

```bash packageManager="npm"
npm install intlayer astro-intlayer svelte svelte-intlayer @astrojs/svelte

npx intlayer init
```

```bash packageManager="pnpm"
pnpm add intlayer astro-intlayer svelte svelte-intlayer @astrojs/svelte

pnpm intlayer init
```

```bash packageManager="yarn"
yarn add intlayer astro-intlayer svelte svelte-intlayer @astrojs/svelte

yarn intlayer init
```

```bash packageManager="bun"
bun add intlayer astro-intlayer svelte svelte-intlayer @astrojs/svelte

bun x intlayer init
```

- **intlayer**
  The core package that provides i18n tools for configuration management, translations, [content declaration](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/dictionary/content_file.md), transpilation, and [CLI commands](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/cli/index.md).

- **astro-intlayer**
  Includes the Astro integration plugin to link Intlayer with the [Vite bundler](https://vite.dev/guide/why.html#why-bundle-for-production), as well as the middleware to detect the user's preferred language, manage cookies, and handle URL redirects.

- **svelte**
  Core Svelte package.

- **svelte-intlayer**
  Package to integrate Intlayer into Svelte applications. It provides `setupIntlayer` as well as the `useIntlayer` and `useLocale` stores for internationalisation in Svelte.

- **@astrojs/svelte**
  Official Astro integration that allows the use of Svelte component islands.

### Step 2: Configure Your Project

Create a configuration file to define your application's languages:

```typescript fileName="intlayer.config.ts"
import { Locales, type IntlayerConfig } from "intlayer";

const config: IntlayerConfig = {
  internationalization: {
    locales: [
      Locales.ENGLISH,
      Locales.FRENCH,
      Locales.SPANISH,
      Locales.ENGLISH_UNITED_KINGDOM,
      // Your other languages
    ],
    defaultLocale: Locales.ENGLISH,
  },
};

export default config;
```

> Through this configuration file, you can configure localised URLs, middleware redirects, cookie names, location and extensions of content declarations, disable Intlayer logs in the console, and more. For a full list of available parameters, refer to the [configuration documentation](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/configuration.md).

### Step 3: Integrate Intlayer into Your Astro Configuration

Add the `intlayer` plugin and Svelte integration to your Astro configuration.

```typescript fileName="astro.config.ts"
// @ts-check

import { intlayer } from "astro-intlayer";
import svelte from "@astrojs/svelte";
import { defineConfig } from "astro/config";

// https://astro.build/config
export default defineConfig({
  integrations: [intlayer(), svelte()],
});
```

> The `intlayer()` integration plugin is used to integrate Intlayer with Astro. It ensures the generation of the content declaration files and monitors them in development mode. It defines Intlayer environment variables within the Astro application and provides aliases to optimise performance.

> The `svelte()` integration allows for using Svelte component islands via `client:only="svelte"`.

### Step 4: Declare Your Content

Create and manage your content declarations to store translations:

```typescript fileName="src/app.content.ts"
import { t, type Dictionary } from "intlayer";

const appContent = {
  key: "app",
  content: {
    title: t({
      en: "Hello World",
      fr: "Bonjour le monde",
      es: "Hola mundo",
      "en-GB": "Hello World",
    }),
  },
} satisfies Dictionary;

export default appContent;
```

> Content declarations can be defined anywhere in your application, as long as they are included in the `contentDir` (by default `./src`) and match the content declaration file extension (by default `.content.{json,ts,tsx,js,jsx,mjs,cjs}`).

> For more information, refer to the [content declaration documentation](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/dictionary/content_file.md).

### Step 5: Using Content in Astro

You can consume the dictionaries directly in your `.astro` files using the core helpers exported from `intlayer`. You should also add SEO metadata (such as hreflang and canonical links) to every page and introduce a Svelte island for interactive client-side content.

```astro fileName="src/pages/[...locale]/index.astro"
---
import {
  getIntlayer,
  getLocaleFromPath,
  getLocalizedUrl,
  getHTMLTextDir,
  getPrefix,
  localeMap,
  defaultLocale,
  type LocalesValues,
} from "intlayer";
import SvelteIsland from "../../components/svelte/SvelteIsland.svelte";

export const getStaticPaths = () => {
  return localeMap(({ locale }) => ({
    params: { locale: getPrefix(locale).localePrefix },
  }));
};

const locale = getLocaleFromPath(Astro.url.pathname) as LocalesValues;
const { title } = getIntlayer("app", locale);
---

<!doctype html>
<html lang={locale} dir={getHTMLTextDir(locale)}>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width" />
    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
    <title>{title}</title>

    <!-- Canonical Link: Informs search engines about the main version of this page -->
    <link
      rel="canonical"
      href={new URL(getLocalizedUrl(Astro.url.pathname, locale), Astro.site)}
    />

    <!-- Hreflang: Informs Google about all localised versions -->
    {
      localeMap(({ locale: mapLocale }) => (
        <link
          rel="alternate"
          hreflang={mapLocale}
          href={new URL(
            getLocalizedUrl(Astro.url.pathname, mapLocale),
            Astro.site
          )}
        />
      ))
    }

    <!-- x-default: Fallback option when locale doesn't match user's language -->
    <link
      rel="alternate"
      hreflang="x-default"
      href={new URL(
        getLocalizedUrl(Astro.url.pathname, defaultLocale),
        Astro.site
      )}
    />
  </head>
  <body>
    <!-- The Svelte island renders all interactive content, including the language switcher -->
    <SvelteIsland locale={locale} client:only="svelte" />
  </body>
</html>
```

> If you want to use your content in a `string` attribute, such as `alt`, `title`, `href`, `aria-label`, etc., you can use the value of the function, like:

> ```html
> <img src="{content.image.src.value}" alt="{content.image.value}" />
> <img src="{content.image.src.toString()}" alt="{content.image.toString()}" />
> <img src="{String(content.image.src)}" alt="{String(content.image)}" />
> ```

> **Note on routing setup:**
> The directory structure you use depends on the `middleware.routing` setting in `intlayer.config.ts`:
>
> - **`prefix-no-default` (default):** keeps the default language at the root (no prefix) and prefixes others. Use `[...locale]` to catch all cases.
> - **`prefix-all`:** all URLs get a language prefix. You can use standard `[locale]` if you don't need to handle the root separately.
> - **`search-param` or `no-prefix`:** no language directories are needed. The language is handled via query parameters or cookies.

### Step 6: Create a Svelte Island Component

Create an island component that wraps your Svelte application. You must call `setupIntlayer` with the server-detected locale before accessing the stores.

```svelte fileName="src/components/svelte/SvelteIsland.svelte"
<script lang="ts">
  import { useIntlayer, useLocale, setupIntlayer } from "svelte-intlayer";
  import { getLocalizedUrl, getLocaleName, type LocalesValues } from "intlayer";

  export let locale: LocalesValues;

  setupIntlayer(locale);

  const content = useIntlayer("app");
  const { locale: currentLocale, availableLocales, setLocale } = useLocale({
    onLocaleChange: (newLocale: LocalesValues) => {
      window.location.href = getLocalizedUrl(window.location.pathname, newLocale);
    },
  });
</script>

<div>
  <h1>{$content.title}</h1>
  <!-- The language switcher is rendered directly within the island -->
  <div class="locale-switcher">
    <span class="switcher-label">Change language:</span>
    <div class="locale-buttons">
      {#each availableLocales as localeItem}
        <button
          class="locale-btn {localeItem === $currentLocale ? 'active' : ''}"
          disabled={localeItem === $currentLocale}
          on:click={() => setLocale(localeItem)}
        >
          <span class="ls-own-name">{getLocaleName(localeItem)}</span>
          <span class="ls-current-name">{getLocaleName(localeItem, $currentLocale)}</span>
          <span class="ls-code">{localeItem.toUpperCase()}</span>
        </button>
      {/each}
    </div>
  </div>
</div>
```

> The `locale` prop is passed from the Astro page (server detection) and used to initialise `setupIntlayer`, setting the initial language for all stores in the component.

### Step 7: Add a Language Switcher

The language switching functionality is integrated directly within the Svelte island (see step 6 above). It uses the `useLocale` store from `svelte-intlayer` and navigates to the localised URL when a user selects a new language:

```svelte fileName="src/components/svelte/SvelteIsland.svelte"
<script lang="ts">
  import { useLocale } from "svelte-intlayer";
  import { getLocalizedUrl, getLocaleName, type LocalesValues } from "intlayer";

  // Reuse the same locale/setupIntlayer logic from step 6...

  const {
    locale: currentLocale,
    availableLocales,
    setLocale,
  } = useLocale({
    onLocaleChange: (newLocale: LocalesValues) => {
      // Navigate to the localised URL on language change
      window.location.href = getLocalizedUrl(window.location.pathname, newLocale);
    },
  });
</script>

<div class="locale-switcher">
  <span class="switcher-label">Change language:</span>
  <div class="locale-buttons">
    {#each availableLocales as localeItem}
      <button
        class="locale-btn {localeItem === $currentLocale ? 'active' : ''}"
        disabled={localeItem === $currentLocale}
        on:click={() => setLocale(localeItem)}
      >
        <span class="ls-own-name">{getLocaleName(localeItem)}</span>
        <span class="ls-current-name">{getLocaleName(localeItem, $currentLocale)}</span>
        <span class="ls-code">{localeItem.toUpperCase()}</span>
      </button>
    {/each}
  </div>
</div>
```

> **Note on persistence:**
> Using `onLocaleChange` to redirect via `window.location.href` ensures the new linguistic URL is visited, allowing the Intlayer middleware to set the language cookie and remember the user's preference in future visits.

### Step 8: Sitemap and Robots.txt

Intlayer offers utilities to dynamically create your localised sitemap and robots.txt files.

#### Sitemap

Intlayer comes with a built-in sitemap generator to help you create a sitemap for your application easily. It handles localized routes and adds the necessary metadata for search engines.

> The Intlayer generated sitemap supports the `xhtml:link` namespace (Hreflang XML Extensions). Unlike the default sitemap generators that only list raw URLs, Intlayer automatically creates the required bidirectional links between all language versions of a page (e.g., `/about`, `/about?lang=fr`, and `/about?lang=es`). This ensures search engines correctly index and serve the right language version to the right audience.

Create `src/pages/sitemap.xml.ts` to generate a sitemap including all your localised routes.

```typescript fileName="src/pages/sitemap.xml.ts"
import type { APIRoute } from "astro";
import { generateSitemap, type SitemapUrlEntry } from "intlayer";

const pathList: SitemapUrlEntry[] = [
  { path: "/", changefreq: "daily", priority: 1.0 },
  { path: "/about", changefreq: "monthly", priority: 0.7 },
];

const SITE_URL = import.meta.env.SITE ?? "http://localhost:4321";

export const GET: APIRoute = async ({ site }) => {
  const xmlOutput = generateSitemap(pathList, { siteUrl: SITE_URL });

  return new Response(xmlOutput, {
    headers: { "Content-Type": "application/xml" },
  });
};
```

#### Robots.txt

Create `src/pages/robots.txt.ts` to control search engine crawling.

```typescript fileName="src/pages/robots.txt.ts"
import type { APIRoute } from "astro";
import { getMultilingualUrls } from "intlayer";

const getAllMultilingualUrls = (urls: string[]) =>
  urls.flatMap((url) => Object.values(getMultilingualUrls(url)) as string[]);

const disallowedPaths = getAllMultilingualUrls(["/admin", "/private"]);

export const GET: APIRoute = ({ site }) => {
  const robotsTxt = [
    "User-agent: *",
    "Allow: /",
    ...disallowedPaths.map((path) => `Disallow: ${path}`),
    "",
    `Sitemap: ${new URL("/sitemap.xml", site).href}`,
  ].join("\n");

  return new Response(robotsTxt, {
    headers: { "Content-Type": "text/plain" },
  });
};
```

### TypeScript Configuration

Intlayer uses module augmentation to leverage TypeScript, making your codebase more robust.

![Autocompletion](https://github.com/aymericzip/intlayer/blob/main/docs/assets/autocompletion.png?raw=true)

![Translation Error](https://github.com/aymericzip/intlayer/blob/main/docs/assets/translation_error.png?raw=true)

Ensure your TypeScript configuration includes the autogenerated types.

```json5 fileName="tsconfig.json"
{
  // ... your existing TypeScript configuration
  "include": [
    // ... your existing TypeScript configuration
    ".intlayer/**/*.ts", // Include autogenerated types
  ],
}
```

### Git Configuration

It is recommended to ignore the files generated by Intlayer. This avoids committing them to your Git repository.

To do this, add the following instructions to your `.gitignore` file:

```bash
# Ignore the files generated by Intlayer
.intlayer
```

### VS Code Extension

To improve your development experience with Intlayer, you can install the **official Intlayer VS Code extension**.

[Installation from the VS Code Marketplace](https://marketplace.visualstudio.com/items?itemName=intlayer.intlayer-vs-code-extension)

This extension provides:

- **Autocompletion** for translation keys.
- **Real-time error detection** for missing translations.
- **Inline preview** of translated content.
- **Quick actions** for easily creating and updating translations.

For more information on using the extension, refer to the [VS Code Extension documentation](https://intlayer.org/doc/vs-code-extension).

---

### (Optional) Step 15: Extract the content of your components

If you have an existing codebase, transforming thousands of files can be time-consuming.

To ease this process, Intlayer propose a [compiler](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/compiler.md) / [extractor](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/cli/extract.md) to transform your components and extract the content.

To set it up, you can add a `compiler` section in your `intlayer.config.ts` file:

```typescript fileName="intlayer.config.ts" codeFormat={["typescript", "esm", "commonjs"]}
import { type IntlayerConfig } from "intlayer";

const config: IntlayerConfig = {
  // ... Rest of your config
  compiler: {
    /**
     * Indicates if the compiler should be enabled.
     */
    enabled: true,

    /**
     * Defines the output files path
     */
    output: ({ fileName, extension }) => `./${fileName}${extension}`,

    /**
     * Indicates if the components should be saved after being transformed.
     *
     * - If `true`, the compiler will rewrite the component file in the disk. So the transformation will be permanent, and the compiler will skip the transformation for the next process. That way, the compiler can transform the app, and then it can be removed.
     *
     * - If `false`, the compiler will inject the `useIntlayer()` function call into the code in the build output only, and keep the base codebase intact. The transformation will be done only in memory.
     */
    saveComponents: false,

    /**
     * Dictionary key prefix
     */
    dictionaryKeyPrefix: "",
  },
};

export default config;
```

<Tabs>
 <Tab value='Extract command'>

Run the extractor to transform your components and extract the content

```bash packageManager="npm"
npx intlayer extract
```

```bash packageManager="pnpm"
pnpm intlayer extract
```

```bash packageManager="yarn"
yarn intlayer extract
```

```bash packageManager="bun"
bun x intlayer extract
```

 </Tab>
 <Tab value='Babel compiler'>

Update your `vite.config.ts` to include the `intlayerCompiler` plugin:

```ts fileName="vite.config.ts"
import { defineConfig } from "vite";
import { intlayer, intlayerCompiler } from "vite-intlayer";

export default defineConfig({
  plugins: [
    intlayer(),
    intlayerCompiler(), // Adds the compiler plugin
  ],
});
```

```bash packageManager="npm"
npm run build # Or npm run dev
```

```bash packageManager="pnpm"
pnpm run build # Or pnpm run dev
```

```bash packageManager="yarn"
yarn build # Or yarn dev
```

```bash packageManager="bun"
bun run build # Or bun run dev
```

 </Tab>
</Tabs>

---

### Deepen Your Knowledge

If you want to learn more, you can also implement the [Visual Editor](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/intlayer_visual_editor.md) or use the [CMS](https://github.com/aymericzip/intlayer/blob/main/docs/docs/en-GB/intlayer_CMS.md) to externalise your content.
