Creation:2024-03-07Last update:2025-10-03

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Getting Started Internationalizing (i18n) with Intlayer and Astro

See Application Template on GitHub.

What is Intlayer?

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

With Intlayer, you can:

Easily manage translations using declarative dictionaries at the component level.
Dynamically localize metadata, routes, and content.
Ensure TypeScript support with autogenerated types, improving autocompletion and error detection.
Benefit from advanced features, like dynamic locale detection and switching.

Step-by-Step Guide to Set Up Intlayer in Astro

Step 1: Install Dependencies

Install the necessary packages using your package manager:

npm install intlayer astro-intlayer# Optional: add React island supportnpm install react react-dom react-intlayer @astrojs/react

intlayer The core package that provides internationalization tools for configuration management, translation, content declaration, transpilation, and CLI commands.
astro-intlayer Includes the Astro integration plugin for integrating Intlayer with the Vite bundler, as well as middleware for detecting the user's preferred locale, managing cookies, and handling URL redirection.

Step 2: Configuration of your project

Create a config file to configure the languages of your application:

intlayer.config.ts

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import { Locales, type IntlayerConfig } from "intlayer";const config: IntlayerConfig = {  internationalization: {    locales: [      Locales.ENGLISH,      Locales.FRENCH,      Locales.SPANISH,      // Your other locales    ],    defaultLocale: Locales.ENGLISH,  },};export default config;

Through this configuration file, you can set up localized URLs, middleware redirection, cookie names, the location and extension of your content declarations, disable Intlayer logs in the console, and more. For a complete list of available parameters, refer to the configuration documentation.

Step 3: Integrate Intlayer in Your Astro Configuration

Add the intlayer plugin into your configuration.

astro.config.ts

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// @ts-checkimport { intlayer } from "astro-intlayer";import { defineConfig } from "astro/config";// https://astro.build/configexport default defineConfig({  integrations: [intlayer()],});

The intlayer() Astro integration plugin is used to integrate Intlayer with Astro. It ensures the building of content declaration files and monitors them in development mode. It defines Intlayer environment variables within the Astro application. Additionally, it provides aliases to optimize performance.

Step 4: Declare Your Content

Create and manage your content declarations to store translations:

src/app.content.tsx

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import { t, type Dictionary } from "intlayer";import type { ReactNode } from "react";const appContent = {  key: "app",  content: {    title: t({      en: "Hello World",      fr: "Bonjour le monde",      es: "Hola mundo",    }),  },} satisfies Dictionary;export default appContent;

Your content declarations can be defined anywhere in your application as soon they are included into the contentDir directory (by default, ./src). And match the content declaration file extension (by default, .content.{json,ts,tsx,js,jsx,mjs,mjx,cjs,cjx}).

For more details, refer to the content declaration documentation.

Step 5: Use your content in Astro

You can consume dictionaries directly in .astro files using the core helpers exported by intlayer.

src/pages/index.astro

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<!-- astro -->---import { getIntlayer } from "intlayer";import appContent from "../app.content";const { title } = getIntlayer('app');---<html lang="en">  <head>    <meta charset="utf-8" />    <meta name="viewport" content="width=device-width" />    <title>{title}</title>  </head>  <body>    <h1>{title}</h1>  </body></html>

Step 6: Localized routing

Create a dynamic route segment to serve localized pages, for example src/pages/[locale]/index.astro:

src/pages/[locale]/index.astro

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<!-- astro -->---import { getIntlayer } from "intlayer";const { title } = getIntlayer('app');---<h1>{title}</h1>

The Astro integration adds a Vite middleware during development that helps with locale-aware routing and environment definitions. You can still link between locales using your own logic, or utility functions like getLocalizedUrl from intlayer.

Step 7: Continue using your favorite framework

Continue using your favorite framework to build your application.

Intlayer + React: Intlayer with React
Intlayer + Vue: Intlayer with Vue
Intlayer + Svelte: Intlayer with Svelte
Intlayer + Solid: Intlayer with Solid
Intlayer + Preact: Intlayer with Preact

Configure TypeScript

Intlayer use module augmentation to get benefits of TypeScript and make your codebase stronger.

alt text

Ensure your TypeScript configuration includes the autogenerated types.

tsconfig.json

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{  // ... Your existing TypeScript configurations  "include": [    // ... Your existing TypeScript configurations    ".intlayer/**/*.ts", // Include the auto-generated types  ],}

Git Configuration

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

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

# 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.

Install from the VS Code Marketplace

This extension provides:

Autocompletion for translation keys.
Real-time error detection for missing translations.
Inline previews of translated content.
Quick actions to easily create and update translations.

For more details on how to use the extension, refer to the Intlayer VS Code Extension documentation.

Go Further

To go further, you can implement the visual editor or externalize your content using the CMS.

Doc History

Version	Date	Changes
6.2.0	2025-10-03	Refresh for Astro integration, config, usage

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