Hreflang & International SEO
Selective Reading Rule
Start with:
references/senior-master-standard.mdreferences/usage-routing.mdreferences/quality-checklist.md
Then load only the inherited docs, scripts, assets, or examples that match the user's actual task.
When to Use
- Use when validating or generating hreflang for multilingual or multiregional sites.
- Use when the user mentions international SEO, language tags, x-default, or hreflang issues.
- Use when auditing locale alternates across HTML, headers, or sitemap implementations.
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 to sitemap for scale)
Error Handling
| Scenario |
Action |
| URL unreachable (DNS failure, connection refused) |
Report the error clearly. Do not guess site structure. Suggest the user verify the URL and try again. |
| No hreflang tags found |
Report the absence. Check for other internationalization signals (subdirectories, subdomains, ccTLDs) and recommend the appropriate hreflang implementation method. |
| Invalid language/region codes detected |
List each invalid code with the correct replacement. Provide a corrected hreflang tag set ready to implement. |
Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
1---2name: seo-hreflang3description: ALWAYS use this when the request matches SEO Hreflang: Hreflang and international SEO audit, validation, and generation.4---56# Hreflang & International SEO78## Selective Reading Rule910Start with:1112- `references/senior-master-standard.md`13- `references/usage-routing.md`14- `references/quality-checklist.md`1516Then load only the inherited docs, scripts, assets, or examples that match the user's actual task.1718## When to Use19- Use when validating or generating hreflang for multilingual or multiregional sites.20- Use when the user mentions international SEO, language tags, x-default, or hreflang issues.21- Use when auditing locale alternates across HTML, headers, or sitemap implementations.2223Validate existing hreflang implementations or generate correct hreflang tags24for multi-language and multi-region sites. Supports HTML, HTTP header, and25XML sitemap implementations.2627## Validation Checks2829### 1. Self-Referencing Tags30- Every page must include an hreflang tag pointing to itself31- The self-referencing URL must exactly match the page's canonical URL32- Missing self-referencing tags cause Google to ignore the entire hreflang set3334### 2. Return Tags35- If page A links to page B with hreflang, page B must link back to page A36- Every hreflang relationship must be bidirectional (A→B and B→A)37- Missing return tags invalidate the hreflang signal for both pages38- Check all language versions reference each other (full mesh)3940### 3. x-default Tag41- Required: designates the fallback page for unmatched languages/regions42- Typically points to the language selector page or English version43- Only one x-default per set of alternates44- Must also have return tags from all other language versions4546### 4. Language Code Validation47- Must use ISO 639-1 two-letter codes (e.g., `en`, `fr`, `de`, `ja`)48- Common errors:49 - `eng` instead of `en` (ISO 639-2, not valid for hreflang)50 - `jp` instead of `ja` (incorrect code for Japanese)51 - `zh` without region qualifier (ambiguous; use `zh-Hans` or `zh-Hant`)5253### 5. Region Code Validation54- Optional region qualifier uses ISO 3166-1 Alpha-2 (e.g., `en-US`, `en-GB`, `pt-BR`)55- Format: `language-REGION` (lowercase language, uppercase region)56- Common errors:57 - `en-uk` instead of `en-GB` (UK is not a valid ISO 3166-1 code)58 - `es-LA` (Latin America is not a country; use specific countries)59 - Region without language prefix6061### 6. Canonical URL Alignment62- Hreflang tags must only appear on canonical URLs63- If a page has `rel=canonical` pointing elsewhere, hreflang on that page is ignored64- The canonical URL and hreflang URL must match exactly (including trailing slashes)65- Non-canonical pages should not be in any hreflang set6667### 7. Protocol Consistency68- All URLs in an hreflang set must use the same protocol (HTTPS or HTTP)69- Mixed HTTP/HTTPS in hreflang sets causes validation failures70- After HTTPS migration, update all hreflang tags to HTTPS7172### 8. Cross-Domain Support73- Hreflang works across different domains (e.g., example.com and example.de)74- Cross-domain hreflang requires return tags on both domains75- Verify both domains are verified in Google Search Console76- Sitemap-based implementation recommended for cross-domain setups7778## Common Mistakes7980| Issue | Severity | Fix |81|-------|----------|-----|82| Missing self-referencing tag | Critical | Add hreflang pointing to same page URL |83| Missing return tags (A→B but no B→A) | Critical | Add matching return tags on all alternates |84| Missing x-default | High | Add x-default pointing to fallback/selector page |85| Invalid language code (e.g., `eng`) | High | Use ISO 639-1 two-letter codes |86| Invalid region code (e.g., `en-uk`) | High | Use ISO 3166-1 Alpha-2 codes |87| Hreflang on non-canonical URL | High | Move hreflang to canonical URL only |88| HTTP/HTTPS mismatch in URLs | Medium | Standardize all URLs to HTTPS |89| Trailing slash inconsistency | Medium | Match canonical URL format exactly |90| Hreflang in both HTML and sitemap | Low | Choose one method (sitemap preferred for large sites) |91| Language without region when needed | Low | Add region qualifier for geo-targeted content |9293## Implementation Methods9495### Method 1: HTML Link Tags96Best for: Sites with <50 language/region variants per page.9798```html99<link rel="alternate" hreflang="en-US" href="https://example.com/page" />100<link rel="alternate" hreflang="en-GB" href="https://example.co.uk/page" />101<link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />102<link rel="alternate" hreflang="x-default" href="https://example.com/page" />103```104105Place in `<head>` section. Every page must include all alternates including itself.106107### Method 2: HTTP Headers108Best for: Non-HTML files (PDFs, documents).109110```111Link: <https://example.com/page>; rel="alternate"; hreflang="en-US",112 <https://example.com/fr/page>; rel="alternate"; hreflang="fr",113 <https://example.com/page>; rel="alternate"; hreflang="x-default"114```115116Set via server configuration or CDN rules.117118### Method 3: XML Sitemap (Recommended for large sites)119Best for: Sites with many language variants, cross-domain setups, or 50+ pages.120121See Hreflang Sitemap Generation section below.122123### Method Comparison124| Method | Best For | Pros | Cons |125|--------|----------|------|------|126| HTML link tags | Small sites (<50 variants) | Easy to implement, visible in source | Bloats `<head>`, hard to maintain at scale |127| HTTP headers | Non-HTML files | Works for PDFs, images | Complex server config, not visible in HTML |128| XML sitemap | Large sites, cross-domain | Scalable, centralized management | Not visible on page, requires sitemap maintenance |129130## Hreflang Generation131132### Process1331. **Detect languages**: Scan site for language indicators (URL path, subdomain, TLD, HTML lang attribute)1342. **Map page equivalents**: Match corresponding pages across languages/regions1353. **Validate language codes**: Verify all codes against ISO 639-1 and ISO 3166-11364. **Generate tags**: Create hreflang tags for each page including self-referencing1375. **Verify return tags**: Confirm all relationships are bidirectional1386. **Add x-default**: Set fallback for each page set1397. **Output**: Generate implementation code (HTML, HTTP headers, or sitemap XML)140141## Hreflang Sitemap Generation142143### Sitemap with Hreflang144```xml145<?xml version="1.0" encoding="UTF-8"?>146<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"147 xmlns:xhtml="http://www.w3.org/1999/xhtml">148 <url>149 <loc>https://example.com/page</loc>150 <xhtml:link rel="alternate" hreflang="en-US" href="https://example.com/page" />151 <xhtml:link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />152 <xhtml:link rel="alternate" hreflang="de" href="https://example.de/page" />153 <xhtml:link rel="alternate" hreflang="x-default" href="https://example.com/page" />154 </url>155 <url>156 <loc>https://example.com/fr/page</loc>157 <xhtml:link rel="alternate" hreflang="en-US" href="https://example.com/page" />158 <xhtml:link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />159 <xhtml:link rel="alternate" hreflang="de" href="https://example.de/page" />160 <xhtml:link rel="alternate" hreflang="x-default" href="https://example.com/page" />161 </url>162</urlset>163```164165Key rules:166- Include the `xmlns:xhtml` namespace declaration167- Every `<url>` entry must include ALL language alternates (including itself)168- Each alternate must appear as a separate `<url>` entry with its own full set169- Split at 50,000 URLs per sitemap file170171## Output172173### Hreflang Validation Report174175#### Summary176- Total pages scanned: XX177- Language variants detected: XX178- Issues found: XX (Critical: X, High: X, Medium: X, Low: X)179180#### Validation Results181| Language | URL | Self-Ref | Return Tags | x-default | Status |182|----------|-----|----------|-------------|-----------|--------|183| en-US | https://... | ✅ | ✅ | ✅ | ✅ |184| fr | https://... | ❌ | ⚠️ | ✅ | ❌ |185| de | https://... | ✅ | ❌ | ✅ | ❌ |186187### Generated Hreflang Tags188- HTML `<link>` tags (if HTML method chosen)189- HTTP header values (if header method chosen)190- `hreflang-sitemap.xml` (if sitemap method chosen)191192### Recommendations193- Missing implementations to add194- Incorrect codes to fix195- Method migration suggestions (e.g., HTML to sitemap for scale)196197## Error Handling198199| Scenario | Action |200|----------|--------|201| URL unreachable (DNS failure, connection refused) | Report the error clearly. Do not guess site structure. Suggest the user verify the URL and try again. |202| No hreflang tags found | Report the absence. Check for other internationalization signals (subdirectories, subdomains, ccTLDs) and recommend the appropriate hreflang implementation method. |203| Invalid language/region codes detected | List each invalid code with the correct replacement. Provide a corrected hreflang tag set ready to implement. |204205## Limitations206- Use this skill only when the task clearly matches the scope described above.207- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.208- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
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