internationalization

name	internationalization
description	Plans multi-locale sites: language-plus-region codes, subfolder vs subdomain vs ccTLD URLs, reciprocal hreflang with self-canonicals, translation workflow, and currency/date/RTL adaptation. Use when adding locales, hreflang, or region-specific formats. Never force Accept-Language redirects; not for iOS .strings catalogs or App Store screenshot locales.
version	1.0.1

When to Use

• Adding the first non-English (or non-default) language to a site.
• Adding additional locales to an existing internationalized site.
• Choosing URL structure for languages (subfolders vs subdomains vs ccTLDs).
• Implementing hreflang tags and canonical strategies.
• Designing translation workflow and content mirroring strategies.
• Handling currency, date, time, and number formats.
• Designing or fixing layout for RTL (Right-to-Left) languages.
• Auditing an internationalization rollout that is underperforming.

Prerequisites

Before starting, gather or confirm the following inputs:

• The locales in scope (language + region, e.g., en-US, de-DE, fr-CA).
• Business reason per locale (priority, audience size).
• Existing site architecture and CMS capabilities.
• Translation resources (in-house, agency, AI-assisted, community).
• Content volume and update frequency.

Procedure

1. Decide Which Locales

Do not add languages just because you can. Each locale has an ongoing maintenance cost.

• Audience research: Where are visitors and prospects located?
• Business priority: Which markets are growth targets?
• Content readiness: Do you have the resources to maintain it?
• Legal: Do regulations require localization (GDPR, accessibility laws)?

2. Pick URL Structure

How locales are reflected in URLs. For most sites, subfolders are the default. Subdomains or ccTLDs only when there's a specific reason (legal, infrastructure, or brand).

Pattern	Example	When to Use
ccTLD	example.de, example.fr	Strong country focus, distinct legal entities, willing to maintain separate domains
Subdomain	de.example.com, fr.example.com	Logical separation, willing to host separately, common for large sites
Subfolder	example.com/de/, example.com/fr/	SEO equity unified, simplest to manage, default for most
URL parameter	example.com?lang=de	Avoid; weak SEO signal

Decide:

• Language only (/de/) or language plus region (/de-de/, /de-at/, /de-ch/)?
• Default locale: at the apex (example.com) or in a folder (example.com/en/)?
  • Note: Default-locale-at-apex is common but causes hreflang complexity (the apex needs an x-default and the canonical for the default language).

3. Pick Content Structure

How content is organized across locales.

• Pattern A: Mirror. Every page in every locale. The translation IS the page. Suitable for marketing sites with controlled content.
• Pattern B: Subset. Some content in all locales, some only in select locales. Common for product pages (only available products), blog (some posts translated), or regulatory differences.
• Pattern C: Local. Each locale has its own content largely independent of other locales. Common for media or community sites.

Most marketing sites are A. Most large sites end up at B by necessity. C is for sites with strong regional editorial.

4. Set up hreflang and Canonicals

Implement before launching the second locale, even if it's just one extra page.

hreflang specifies the language and optional region for each version.

<link rel="alternate" hreflang="en-US" href="https://example.com/en-us/page">
<link rel="alternate" hreflang="en-GB" href="https://example.com/en-gb/page">
<link rel="alternate" hreflang="de-DE" href="https://example.com/de-de/page">
<link rel="alternate" hreflang="x-default" href="https://example.com/en-us/page">

Rules:

• Every page lists every translated equivalent (including itself).
• Pages must reciprocate (page A says page B is its German version; page B says page A is its English version).
• x-default is the fallback for users in unspecified regions.
• Each page has its own canonical pointing to itself (not to the default language).
• hreflang can be in the HTML head, in HTTP headers, or in the XML sitemap. Sitemap is best for large sites; HTML head is fine for small.

5. Set up Translation Workflow

How content gets translated, kept fresh, and quality-controlled.

1. Source content authored in the source language.
2. Translation requested through a TMS (translation management system) or spreadsheet.
3. Translation produced with translation memory (avoids retranslating reused phrases).
4. Review by a second translator or in-region staff.
5. Localization beyond translation (currency, units, examples, cultural references).
6. Publishing in the destination locale.
7. Update propagation when source content changes.

The TMS pays off above ~10K words of total content. Below that, spreadsheets and disciplined naming are fine.

6. Localize Beyond Translation

For each locale, adapt the experience:

• Currency: Display in the local currency where applicable (EUR for European locales, JPY for Japanese). Don't show USD to French users.
• Numbers: Thousand separators and decimals differ (1,000.50 in en-US is 1.000,50 in de-DE).
• Dates and times: Format and order vary. Use a date formatting library that respects locale.
• Names and addresses: Field order and required components differ. Use country-aware address forms.
• Phone numbers: E.164 international format universally; display formatting per locale.
• Units: Metric vs imperial.
• RTL languages: Arabic, Hebrew, Persian, Urdu. Layout flips. Use CSS logical properties (margin-inline-start instead of margin-left).
• Cultural sensitivity: Avoid hand gestures in product imagery. Avoid country-specific references unless localized.

7. Implement Language Switcher

• Prominent in the header or footer.
• Shows the current locale clearly.
• Lists all available locales in their own language ("Deutsch" not "German").
• Persists the choice (cookie or local storage).
• Doesn't auto-redirect based on browser; suggests instead.
• Try to land the user on the same page in the new locale, not the homepage.

8. Test

• Each locale renders correctly.
• hreflang links are valid (use a checker).
• Canonicals are self-referential per page.
• Currency and dates are correct.
• RTL layout is correct (for RTL locales).
• Language switcher works and persists.
• Search-engine perspective: each locale is crawlable and indexable.

9. Launch and Monitor

Per locale, monitor:

• Indexing rate.
• Traffic from intended geographies.
• Engagement metrics in the locale.
• Translation freshness (when did source content change without translation update?).

10. Maintain

• Translation update cadence (when source changes, when translations follow).
• Quarterly review of locale performance.
• Sunset locales that aren't viable (better than maintaining a dead locale poorly). Redirect old URLs to the closest equivalent in another supported language.

Pitfalls

• Auto-redirect based on browser language: User is in Germany, prefers English. Site forces German. Suggest, don't redirect.
• Single canonical to default language: Search engines can't index the translations. Self-canonical per page.
• Reciprocal hreflang missing: German page lists English as its translation, English page doesn't list German. Search engines treat the relationship as unconfirmed.
• hreflang language without region when region matters: hreflang="es" is fine if there's one Spanish version. If you have es-ES (Spain) and es-MX (Mexico), use both with regions.
• Auto-translated content treated as final: Machine translation is an acceptable starting point. Human review is necessary for any user-facing content.
• Currency baked into copy: "$99/month" in body text breaks for European users. Use templated currency that adapts.
• Hardcoded date formats: "January 5, 2024" in code. Doesn't adapt. Use a date formatting library.
• Field labels left in source language: Translated body, untranslated form labels. Translate UI strings as part of localization.
• Untranslated error messages: User submits a form, gets an error in English on a French page. Translate UI states.
• Untranslated emails: Site is in French; transactional emails are English. Translate emails to match.
• Forgotten locales in CMS: Editors forget to update one locale. Drift. Use a TMS or workflow that surfaces drift.
• Locale switcher that doesn't work mid-flow: User is on the German checkout, switches to French, lands on French homepage. Try to land on the same page in the new locale.
• RTL layouts that don't actually flip: Margin and padding hardcoded for LTR. Use CSS logical properties.
• Sunset language without redirect: Discontinuing French; old French URLs 404. Redirect to the closest equivalent in another supported language.

Verification

To verify the internationalization rollout:

1. Crawl the site: Use a crawler (e.g., Screaming Frog) to verify all hreflang tags are present, reciprocated, and valid.
2. Check canonicals: Ensure every locale page has a self-referential canonical.
3. Visual check: Manually verify currency, dates, and numbers render correctly per locale.
4. RTL check: If supporting RTL, verify layout flips correctly and no hardcoded LTR margins/paddings exist.
5. Switcher test: Change languages and verify the user lands on the equivalent page and the choice persists on reload.
6. Search Console: Check indexing status for each locale-specific URL pattern.

Per-locale extras

Cover URL pattern, content mirroring, UX (switcher, RTL), formats (currency, dates, numbers), and legal copy in Procedure steps 2–7. This folder does not ship a separate locale checklist file. Official hreflang: https://developers.google.com/search/docs/specialty/international/localized-versions