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Version History
- "Update Solid useIntlayer API usage to direct property access"v8.9.004/05/2026
- "Add init command"v7.5.930/12/2025
- "Update documentation"v5.5.1119/11/2025
- "Initial history"v5.5.1029/06/2025
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Translate your Vite and Svelte website using Intlayer | Internationalisation (i18n)
Table of Contents
Why Intlayer over alternatives?
Compared to main solutions like svelte-i18n or i18next, Intlayer is a solution that comes with integrated optimizations such as:
Intlayer is optimized to work perfectly with Svelte by offering component-level content scoping, reactive translations, and all the features needed for scaling internationalization (i18n).
Instead of loading massive JSON files into your pages, load only the necessary content. Intlayer helps reduce your bundle and page sizes by up to 50%.
Scoping your application's content facilitates maintenance for large-scale applications. You can duplicate or delete a single feature folder without the mental burden of reviewing your entire content codebase. Additionally, Intlayer is fully typed to ensure your content's accuracy.
Co-locating content reduces the context needed by Large Language Models (LLMs). Intlayer also comes with a suite of tools, such as a CLI to test for missing translations,LSP, MCP, and agent skills, to make the developer experience (DX) even smoother for AI agents.
Use automation to translate in your CI/CD pipeline using the LLM of your choice at the cost of your AI provider. Intlayer also offers a compiler to automate content extraction, as well as a web platform to help translate in the background.
Connecting massive JSON files to components can lead to performance and reactivity issues. Intlayer optimizes your content loading at build time.
More than just an i18n solution, Intlayer provides an self-hosted visual editor and a full CMS to help you manage your multilingual content in real-time, making collaboration with translators, copywriters, and other team members seamless. Content can be stored locally and/or remotely.
Step-by-Step Guide to Set Up Intlayer in a Vite and Svelte Application
See Application Template on GitHub.
Install Dependencies
Install the necessary packages using npm:
bashCopy codeCopy the code to the clipboard
intlayer
The core package that provides internationalisation tools for configuration management, translation, content declaration, transpilation, and CLI commands.
svelte-intlayer The package that integrates Intlayer with Svelte applications. It provides context providers and hooks for Svelte internationalisation.
vite-intlayer Includes the Vite 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.
Configuration of your project
Create a config file to configure the languages of your application:
intlayer.config.tsCopy codeCopy the code to the clipboard
Through this configuration file, you can set up localised 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.
Integrate Intlayer in Your Vite Configuration
Add the intlayer plugin into your configuration.
vite.config.tsCopy codeCopy the code to the clipboard
The
intlayer()Vite plugin is used to integrate Intlayer with Vite. It ensures the building of content declaration files and monitors them in development mode. It defines Intlayer environment variables within the Vite application. Additionally, it provides aliases to optimise performance.Declare Your Content
Create and manage your content declarations to store translations:
src/app.content.tsxCopy codeCopy the code to the clipboard
import { t, type Dictionary } from "intlayer"; 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 as they are included in the
contentDirdirectory (by default,./src). And match the content declaration file extension (by default,.content.{json,ts,tsx,js,jsx,mjs,cjs,md,mdx,yaml,yml}).For more details, refer to the content declaration documentation.
Utilise Intlayer in Your Code
src/App.svelteCopy codeCopy the code to the clipboard
Change the language of your content
Optionalsrc/App.svelteCopy codeCopy the code to the clipboard
Render Markdown
OptionalIntlayer supports rendering Markdown content directly in your Svelte application. By default, Markdown is treated as plain text. To convert Markdown into rich HTML, you can integrate
@humanspeak/svelte-markdown, or another markdown parser.To see how to declare markdown content using the
intlayerpackage, see the markdown doc.src/App.svelteCopy codeCopy the code to the clipboard
You can also access your markdown front-matter data using the
content.markdownContent.metadata.xxxproperty.Set up the intlayer editor / CMS
OptionalTo set up the intlayer editor, you must follow the intlayer editor documentation.
To set up the intlayer CMS, you must follow the intlayer CMS documentation.
Add localised Routing to your application
OptionalTo handle localised routing in your Svelte application, you can use
svelte-spa-routeralong with Intlayer'slocaleFlatMapto generate routes for each locale.First, install
svelte-spa-router:bashCopy codeCopy the code to the clipboard
Then, create a
Router.sveltefile to define your routes:src/Router.svelteCopy codeCopy the code to the clipboard
Update your
main.tsto mount theRoutercomponent instead ofApp:src/main.tsCopy codeCopy the code to the clipboard
Finally, update your
App.svelteto receive thelocaleprop and use it withuseIntlayer:src/App.svelteCopy codeCopy the code to the clipboard
Configure Server-Side Routing (Optional)
In parallel, you can also use the
intlayerProxyto add server-side routing to your application. This plugin will automatically detect the current locale based on the URL and set the appropriate locale cookie. If no locale is specified, the plugin will determine the most appropriate locale based on the user's browser language preferences. If no locale is detected, it will redirect to the default locale.Note that to use the
intlayerProxyin production, you need to switch thevite-intlayerpackage fromdevDependenciestodependencies.vite.config.tsCopy codeCopy the code to the clipboard
import { defineConfig } from "vite"; import { svelte } from "@sveltejs/vite-plugin-svelte"; import { intlayer, intlayerProxy } from "vite-intlayer"; // https://vitejs.dev/config/ export default defineConfig({ plugins: [ intlayerProxy(), // should be placed first svelte(), intlayer(), ], });Change the URL when the locale changes
OptionalTo allow users to switch languages and update the URL accordingly, you can create a
LocaleSwitchercomponent. This component will usegetLocalizedUrlfromintlayerandpushfromsvelte-spa-router.src/lib/LocaleSwitcher.svelteCopy codeCopy the code to the clipboard
(Optional) Sitemap and robots.txt (build-time)
Intlayer includes formatters such as generateSitemap and getMultilingualUrls that produce crawler-ready multilingual sitemap.xml and robots.txt output you can write into your project’s public/ folder. In practice you run a small Node script before Vite (for example predev / prebuild npm hooks) so those files exist when you build or serve the app.
Sitemap
Intlayer’s sitemap generator respects your locale setup and includes the usual metadata for crawlers.
The generated sitemap supports thexhtml:linknamespace (hreflang XML extensions). Unlike basic generators that only emit flat URLs, Intlayer wires bidirectional links between every localized variant of each page (for example/about,/fr/about, or/about?lang=fr, depending on your routing mode), which helps search engines relate localized URLs.
Robots.txt
Use getMultilingualUrls so Disallow entries cover every localized spelling of sensitive paths.
1. Add generate-seo.mjs at the project root
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intlayer must be installed so the script can import it. Set SITE_URL in the environment for production (for example in CI).
Prefergenerate-seo.mjsfor Node ESM. If you usegenerate-seo.jsinstead, ensure"type": "module"is set inpackage.json, or run Node with ESM enabled.
2. Run the script before Vite
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Adjust if you use pnpm or yarn. You can also invoke the same script from CI or another step if that fits your workflow.
Git Configuration
It is recommended to ignore the files generated by Intlayer. This prevents you from committing them to your Git repository.
To do this, you can add the following instructions to your .gitignore file:
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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 externalise your content using the CMS.