vitepress/docs/guide/i18n.md

Internationalization

To use the built-in i18n features, one needs to create a directory structure as follows:

docs/
├─ es/
│  ├─ foo.md
├─ fr/
│  ├─ foo.md
├─ foo.md

Then in docs/.vitepress/config.ts:

import { defineConfig } from 'vitepress'

export default defineConfig({
  // shared properties and other top-level stuff...

  locales: {
    root: {
      label: 'English',
      lang: 'en'
    },
    fr: {
      label: 'French',
      lang: 'fr', // optional, will be added  as `lang` attribute on `html` tag
      link: '/fr/guide' // default /fr/ -- shows on navbar translations menu, can be external

      // other locale specific properties...
    }
  }
})

The following properties can be overridden for each locale (including root):

interface LocaleSpecificConfig<ThemeConfig = any> {
  lang?: string
  dir?: string
  title?: string
  titleTemplate?: string | boolean
  description?: string
  head?: HeadConfig[] // will be merged with existing head entries, duplicate meta tags are automatically removed
  themeConfig?: ThemeConfig // will be shallow merged, common stuff can be put in top-level themeConfig entry
}

Refer DefaultTheme.Config interface for details on customizing the placeholder texts of the default theme. Don't override themeConfig.algolia or themeConfig.carbonAds at locale-level. Refer Algolia docs for using multilingual search.

Pro tip: Config file can be stored at docs/.vitepress/config/index.ts too. It might help you organize stuff by creating a configuration file per locale and then merge and export them from index.ts.

Separate directory for each locale

The following is a perfectly fine structure:

docs/
├─ en/
│  ├─ foo.md
├─ es/
│  ├─ foo.md
├─ fr/
   ├─ foo.md

However, VitePress won't redirect / to /en/ by default. You'll need to configure your server for that. For example, on Netlify, you can add a docs/public/_redirects file like this:

/*  /es/:splat  302  Language=es
/*  /fr/:splat  302  Language=fr
/*  /en/:splat  302

Pro tip: If using the above approach, you can use nf_lang cookie to persist user's language choice. A very basic way to do this is register a watcher inside the setup function of custom theme:

// docs/.vitepress/theme/index.ts
import DefaultTheme from 'vitepress/theme'

export default {
  ...DefaultTheme,
  setup() {
    const { lang } = useData()
    watchEffect(() => {
      if (inBrowser) {
        document.cookie = `nf_lang=${lang.value}; expires=Mon, 1 Jan 2024 00:00:00 UTC; path=/`
      }
    })
  }
}

RTL Support (Experimental)

For RTL support, specify dir: 'rtl' in config and use some RTLCSS PostCSS plugin like https://github.com/MohammadYounes/rtlcss, https://github.com/vkalinichev/postcss-rtl or https://github.com/elchininet/postcss-rtlcss. You'll need to configure your PostCSS plugin to use :where([dir="ltr"]) and :where([dir="rtl"]) as prefixes to prevent CSS specificity issues.