Hreflang & International SEO
Validate existing hreflang implementations or generate correct hreflang tags
for multi-language and multi-region sites. Supports HTML, HTTP header, and
XML sitemap implementations.
Validation Checks
1. Self-Referencing Tags
- Every page must include an hreflang tag pointing to itself
- The self-referencing URL must exactly match the page's canonical URL
- Missing self-referencing tags cause Google to ignore the entire hreflang set
2. Return Tags
- If page A links to page B with hreflang, page B must link back to page A
- Every hreflang relationship must be bidirectional (A→B and B→A)
- Missing return tags invalidate the hreflang signal for both pages
- Check all language versions reference each other (full mesh)
3. x-default Tag
- Required: designates the fallback page for unmatched languages/regions
- Typically points to the language selector page or English version
- Only one x-default per set of alternates
- Must also have return tags from all other language versions
4. Language Code Validation
- Must use ISO 639-1 two-letter codes (e.g.,
en, fr, de, ja)
- Common errors:
eng instead of en (ISO 639-2, not valid for hreflang)jp instead of ja (incorrect code for Japanese)zh without region qualifier (ambiguous — use zh-Hans or zh-Hant)
5. Region Code Validation
- Optional region qualifier uses ISO 3166-1 Alpha-2 (e.g.,
en-US, en-GB, pt-BR)
- Format:
language-REGION (lowercase language, uppercase region)
- Common errors:
en-uk instead of en-GB (UK is not a valid ISO 3166-1 code)es-LA (Latin America is not a country — use specific countries)- Region without language prefix
6. Canonical URL Alignment
- Hreflang tags must only appear on canonical URLs
- If a page has
rel=canonical pointing elsewhere, hreflang on that page is ignored
- The canonical URL and hreflang URL must match exactly (including trailing slashes)
- Non-canonical pages should not be in any hreflang set
7. Protocol Consistency
- All URLs in an hreflang set must use the same protocol (HTTPS or HTTP)
- Mixed HTTP/HTTPS in hreflang sets causes validation failures
- After HTTPS migration, update all hreflang tags to HTTPS
8. Cross-Domain Support
- Hreflang works across different domains (e.g., example.com and example.de)
- Cross-domain hreflang requires return tags on both domains
- Verify both domains are verified in Google Search Console
- Sitemap-based implementation recommended for cross-domain setups
Common Mistakes
| Issue |
Severity |
Fix |
| Missing self-referencing tag |
Critical |
Add hreflang pointing to same page URL |
| Missing return tags (A→B but no B→A) |
Critical |
Add matching return tags on all alternates |
| Missing x-default |
High |
Add x-default pointing to fallback/selector page |
Invalid language code (e.g., eng) |
High |
Use ISO 639-1 two-letter codes |
Invalid region code (e.g., en-uk) |
High |
Use ISO 3166-1 Alpha-2 codes |
| Hreflang on non-canonical URL |
High |
Move hreflang to canonical URL only |
| HTTP/HTTPS mismatch in URLs |
Medium |
Standardize all URLs to HTTPS |
| Trailing slash inconsistency |
Medium |
Match canonical URL format exactly |
| Hreflang in both HTML and sitemap |
Low |
Choose one method — sitemap preferred for large sites |
| Language without region when needed |
Low |
Add region qualifier for geo-targeted content |
Implementation Methods
Method 1: HTML Link Tags
Best for: Sites with <50 language/region variants per page.
<link rel="alternate" hreflang="en-US" href="https://example.com/page" />
<link rel="alternate" hreflang="en-GB" href="https://example.co.uk/page" />
<link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />
<link rel="alternate" hreflang="x-default" href="https://example.com/page" />
Place in <head> section. Every page must include all alternates including itself.
Method 2: HTTP Headers
Best for: Non-HTML files (PDFs, documents).
Link: <https://example.com/page>; rel="alternate"; hreflang="en-US",
<https://example.com/fr/page>; rel="alternate"; hreflang="fr",
<https://example.com/page>; rel="alternate"; hreflang="x-default"
Set via server configuration or CDN rules.
Method 3: XML Sitemap (Recommended for large sites)
Best for: Sites with many language variants, cross-domain setups, or 50+ pages.
See Hreflang Sitemap Generation section below.
Method Comparison
| Method |
Best For |
Pros |
Cons |
| HTML link tags |
Small sites (<50 variants) |
Easy to implement, visible in source |
Bloats <head>, hard to maintain at scale |
| HTTP headers |
Non-HTML files |
Works for PDFs, images |
Complex server config, not visible in HTML |
| XML sitemap |
Large sites, cross-domain |
Scalable, centralized management |
Not visible on page, requires sitemap maintenance |
Hreflang Generation
Process
- Detect languages: Scan site for language indicators (URL path, subdomain, TLD, HTML lang attribute)
- Map page equivalents: Match corresponding pages across languages/regions
- Validate language codes: Verify all codes against ISO 639-1 and ISO 3166-1
- Generate tags: Create hreflang tags for each page including self-referencing
- Verify return tags: Confirm all relationships are bidirectional
- Add x-default: Set fallback for each page set
- Output: Generate implementation code (HTML, HTTP headers, or sitemap XML)
Hreflang Sitemap Generation
Sitemap with Hreflang
<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
xmlns:xhtml="http://www.w3.org/1999/xhtml">
<url>
<loc>https://example.com/page</loc>
<xhtml:link rel="alternate" hreflang="en-US" href="https://example.com/page" />
<xhtml:link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />
<xhtml:link rel="alternate" hreflang="de" href="https://example.de/page" />
<xhtml:link rel="alternate" hreflang="x-default" href="https://example.com/page" />
</url>
<url>
<loc>https://example.com/fr/page</loc>
<xhtml:link rel="alternate" hreflang="en-US" href="https://example.com/page" />
<xhtml:link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />
<xhtml:link rel="alternate" hreflang="de" href="https://example.de/page" />
<xhtml:link rel="alternate" hreflang="x-default" href="https://example.com/page" />
</url>
</urlset>
Key rules:
- Include the
xmlns:xhtml namespace declaration
- Every
<url> entry must include ALL language alternates (including itself)
- Each alternate must appear as a separate
<url> entry with its own full set
- Split at 50,000 URLs per sitemap file
Output
Hreflang Validation Report
Summary
- Total pages scanned: XX
- Language variants detected: XX
- Issues found: XX (Critical: X, High: X, Medium: X, Low: X)
Validation Results
| Language |
URL |
Self-Ref |
Return Tags |
x-default |
Status |
| en-US |
https://... |
✅ |
✅ |
✅ |
✅ |
| fr |
https://... |
❌ |
⚠️ |
✅ |
❌ |
| de |
https://... |
✅ |
❌ |
✅ |
❌ |
Generated Hreflang Tags
- HTML
<link> tags (if HTML method chosen)
- HTTP header values (if header method chosen)
hreflang-sitemap.xml (if sitemap method chosen)
Recommendations
- Missing implementations to add
- Incorrect codes to fix
- Method migration suggestions (e.g., HTML → sitemap for scale)
[PROTOCOL]: Update this header on changes, then check CLAUDE.md
1---2name: 30x-seo-hreflang3description: Hreflang and international SEO audit, validation, and generation. Detects common mistakes, validates language/region codes, and generates correct hreflang implementations. Use when user says "hreflang", "i18n SEO", "international SEO", "multi-language", "multi-region", or "language tags".4---56# Hreflang & International SEO78Validate existing hreflang implementations or generate correct hreflang tags9for multi-language and multi-region sites. Supports HTML, HTTP header, and10XML sitemap implementations.1112## Validation Checks1314### 1. Self-Referencing Tags15- Every page must include an hreflang tag pointing to itself16- The self-referencing URL must exactly match the page's canonical URL17- Missing self-referencing tags cause Google to ignore the entire hreflang set1819### 2. Return Tags20- If page A links to page B with hreflang, page B must link back to page A21- Every hreflang relationship must be bidirectional (A→B and B→A)22- Missing return tags invalidate the hreflang signal for both pages23- Check all language versions reference each other (full mesh)2425### 3. x-default Tag26- Required: designates the fallback page for unmatched languages/regions27- Typically points to the language selector page or English version28- Only one x-default per set of alternates29- Must also have return tags from all other language versions3031### 4. Language Code Validation32- Must use ISO 639-1 two-letter codes (e.g., `en`, `fr`, `de`, `ja`)33- Common errors:34 - `eng` instead of `en` (ISO 639-2, not valid for hreflang)35 - `jp` instead of `ja` (incorrect code for Japanese)36 - `zh` without region qualifier (ambiguous — use `zh-Hans` or `zh-Hant`)3738### 5. Region Code Validation39- Optional region qualifier uses ISO 3166-1 Alpha-2 (e.g., `en-US`, `en-GB`, `pt-BR`)40- Format: `language-REGION` (lowercase language, uppercase region)41- Common errors:42 - `en-uk` instead of `en-GB` (UK is not a valid ISO 3166-1 code)43 - `es-LA` (Latin America is not a country — use specific countries)44 - Region without language prefix4546### 6. Canonical URL Alignment47- Hreflang tags must only appear on canonical URLs48- If a page has `rel=canonical` pointing elsewhere, hreflang on that page is ignored49- The canonical URL and hreflang URL must match exactly (including trailing slashes)50- Non-canonical pages should not be in any hreflang set5152### 7. Protocol Consistency53- All URLs in an hreflang set must use the same protocol (HTTPS or HTTP)54- Mixed HTTP/HTTPS in hreflang sets causes validation failures55- After HTTPS migration, update all hreflang tags to HTTPS5657### 8. Cross-Domain Support58- Hreflang works across different domains (e.g., example.com and example.de)59- Cross-domain hreflang requires return tags on both domains60- Verify both domains are verified in Google Search Console61- Sitemap-based implementation recommended for cross-domain setups6263## Common Mistakes6465| Issue | Severity | Fix |66|-------|----------|-----|67| Missing self-referencing tag | Critical | Add hreflang pointing to same page URL |68| Missing return tags (A→B but no B→A) | Critical | Add matching return tags on all alternates |69| Missing x-default | High | Add x-default pointing to fallback/selector page |70| Invalid language code (e.g., `eng`) | High | Use ISO 639-1 two-letter codes |71| Invalid region code (e.g., `en-uk`) | High | Use ISO 3166-1 Alpha-2 codes |72| Hreflang on non-canonical URL | High | Move hreflang to canonical URL only |73| HTTP/HTTPS mismatch in URLs | Medium | Standardize all URLs to HTTPS |74| Trailing slash inconsistency | Medium | Match canonical URL format exactly |75| Hreflang in both HTML and sitemap | Low | Choose one method — sitemap preferred for large sites |76| Language without region when needed | Low | Add region qualifier for geo-targeted content |7778## Implementation Methods7980### Method 1: HTML Link Tags81Best for: Sites with <50 language/region variants per page.8283```html84<link rel="alternate" hreflang="en-US" href="https://example.com/page" />85<link rel="alternate" hreflang="en-GB" href="https://example.co.uk/page" />86<link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />87<link rel="alternate" hreflang="x-default" href="https://example.com/page" />88```8990Place in `<head>` section. Every page must include all alternates including itself.9192### Method 2: HTTP Headers93Best for: Non-HTML files (PDFs, documents).9495```96Link: <https://example.com/page>; rel="alternate"; hreflang="en-US",97 <https://example.com/fr/page>; rel="alternate"; hreflang="fr",98 <https://example.com/page>; rel="alternate"; hreflang="x-default"99```100101Set via server configuration or CDN rules.102103### Method 3: XML Sitemap (Recommended for large sites)104Best for: Sites with many language variants, cross-domain setups, or 50+ pages.105106See Hreflang Sitemap Generation section below.107108### Method Comparison109| Method | Best For | Pros | Cons |110|--------|----------|------|------|111| HTML link tags | Small sites (<50 variants) | Easy to implement, visible in source | Bloats `<head>`, hard to maintain at scale |112| HTTP headers | Non-HTML files | Works for PDFs, images | Complex server config, not visible in HTML |113| XML sitemap | Large sites, cross-domain | Scalable, centralized management | Not visible on page, requires sitemap maintenance |114115## Hreflang Generation116117### Process1181. **Detect languages**: Scan site for language indicators (URL path, subdomain, TLD, HTML lang attribute)1192. **Map page equivalents**: Match corresponding pages across languages/regions1203. **Validate language codes**: Verify all codes against ISO 639-1 and ISO 3166-11214. **Generate tags**: Create hreflang tags for each page including self-referencing1225. **Verify return tags**: Confirm all relationships are bidirectional1236. **Add x-default**: Set fallback for each page set1247. **Output**: Generate implementation code (HTML, HTTP headers, or sitemap XML)125126## Hreflang Sitemap Generation127128### Sitemap with Hreflang129```xml130<?xml version="1.0" encoding="UTF-8"?>131<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"132 xmlns:xhtml="http://www.w3.org/1999/xhtml">133 <url>134 <loc>https://example.com/page</loc>135 <xhtml:link rel="alternate" hreflang="en-US" href="https://example.com/page" />136 <xhtml:link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />137 <xhtml:link rel="alternate" hreflang="de" href="https://example.de/page" />138 <xhtml:link rel="alternate" hreflang="x-default" href="https://example.com/page" />139 </url>140 <url>141 <loc>https://example.com/fr/page</loc>142 <xhtml:link rel="alternate" hreflang="en-US" href="https://example.com/page" />143 <xhtml:link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />144 <xhtml:link rel="alternate" hreflang="de" href="https://example.de/page" />145 <xhtml:link rel="alternate" hreflang="x-default" href="https://example.com/page" />146 </url>147</urlset>148```149150Key rules:151- Include the `xmlns:xhtml` namespace declaration152- Every `<url>` entry must include ALL language alternates (including itself)153- Each alternate must appear as a separate `<url>` entry with its own full set154- Split at 50,000 URLs per sitemap file155156## Output157158### Hreflang Validation Report159160#### Summary161- Total pages scanned: XX162- Language variants detected: XX163- Issues found: XX (Critical: X, High: X, Medium: X, Low: X)164165#### Validation Results166| Language | URL | Self-Ref | Return Tags | x-default | Status |167|----------|-----|----------|-------------|-----------|--------|168| en-US | https://... | ✅ | ✅ | ✅ | ✅ |169| fr | https://... | ❌ | ⚠️ | ✅ | ❌ |170| de | https://... | ✅ | ❌ | ✅ | ❌ |171172### Generated Hreflang Tags173- HTML `<link>` tags (if HTML method chosen)174- HTTP header values (if header method chosen)175- `hreflang-sitemap.xml` (if sitemap method chosen)176177### Recommendations178- Missing implementations to add179- Incorrect codes to fix180- Method migration suggestions (e.g., HTML → sitemap for scale)181182[PROTOCOL]: Update this header on changes, then check CLAUDE.md
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