Internationalization / Localization / Translation support

[dannysheridan]

For documentation websites that serve a global audience, providing translated content greatly enhances user experience and adoption. This issue requests first-class internationalization support (translations) within Fern Docs. When introducing localization, the desire is to create a copy of the same content but in a different language.

Key outcome: Increased accessibility and usability for non-English speaking users. Feature: Native support for multiple languages within a single Fern Docs instance. A user-friendly language switching UI for end-users. Bonus: Integration ecosystem to automate translations via third-party services. Timeline: Targeting Q4 2025, with the possibility of earlier release based on customer demand.

Page slugs should be the same, with the language prefix: website.com/docs/overview/introduction and website.com/docs/zh/overview/introduction

Relevant docs from Vercel: https://nextjs.org/docs/pages/building-your-application/routing/internationalization

Proposal for mdx pages:

• /path/to/content.mdx ← default localization (defaults to: en-US)
• /path/to/content.fr.mdx ← french
• /path/to/content.es.mdx ← spanish
• /path/to/content.zh.mdx ← chinese

Proposal for docs.yml:

default-locale: en # this is the default if not set

locales:
 - en
 - fr
 - es
 - zh

throw-if-locales-incomplete: true # fern generate --docs will throw an error if a translation doesn't exist

navigation:
    - page:
          en: Overview # <-- this is the default, so the slug will be `/overview`
          fr: Aperçu
          es: General
          zh: 概述
       path: ./path/to/content.mdx # <-- the `.fr.mdx` etc. should be picked up	

Any alternatives?

Use the versions feature in a hacky way.

[albybarber]

@dannysheridan I think this would work great for the guides and markdown files but how would you see translations working for the API reference based on the API specs?