Skills Guide

Hreflang & International SEO

VerifiedCaution

Audit, validate, and generate hreflang tags for international SEO. Detects common mistakes and validates language/region codes.

Sby Skills Guide Bot
ContentIntermediate
108/29/2026
Claude Code
#seo#hreflang#international-seo#multilingual#localization

Recommended for

Claude CodeUI/UX designerSEO & contentProduct managerWriter / marketerSolo / indie hacker

Our review

Validates and generates hreflang tags and international SEO configurations across HTML, HTTP headers, and XML sitemaps.

Strengths

  • Covers all major hreflang implementation formats (HTML, headers, sitemaps).
  • Detects critical issues like missing self-referencing tags, broken return tags, and invalid locale codes.
  • Provides concrete fixes and severity ratings for common mistakes.

Limitations

  • Does not cover JavaScript-rendered hreflang or dynamic client-side alternates.
  • Requires manual verification of site canonicalization beyond the checks listed.
  • May need WebFetch access and proper site credentials for cross-domain audits.
When to use it

Use when auditing or building hreflang setups for multilingual or multi-region websites.

When not to use it

Do not use for single-language sites or when the user needs broader SEO audits beyond locale targeting.

Security analysis

Caution
Quality score88/100

The skill is an instructional guide for hreflang SEO validation and generation. It does not contain explicit dangerous commands, but it permits Bash and WebFetch, which are powerful tools that can be used for network requests and local command execution. The risk is low but non-zero, primarily from potential misuse rather than the skill's own content.

Findings
  • •Uses WebFetch to retrieve remote pages, which may fetch untrusted content.
  • •Allows Bash tool, which could execute arbitrary commands if instructions are manipulated, though the skill itself does not contain destructive commands.

Examples

Validate existing hreflang
Audit the hreflang implementation on https://example.com and check for missing return tags, self-referencing tags, and x-default.
Generate hreflang tags
Generate correct hreflang tags for my English, French, and German versions of https://example.com using the en-US, fr-FR, and de-DE locale codes.
Fix invalid locale codes
My site uses 'en-uk' and 'eng' in hreflang tags — identify the correct ISO codes and generate the fix.

name: seo-hreflang description: > 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". risk: unknown source: "https://github.com/AgriciDaniel/claude-seo" date_added: "2026-03-21" user-invokable: true argument-hint: "[url]" allowed-tools:

  • Read
  • Grep
  • Glob
  • Bash
  • WebFetch

Hreflang & International SEO

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

  1. Detect languages: Scan site for language indicators (URL path, subdomain, TLD, HTML lang attribute)
  2. Map page equivalents: Match corresponding pages across languages/regions
  3. Validate language codes: Verify all codes against ISO 639-1 and ISO 3166-1
  4. Generate tags: Create hreflang tags for each page including self-referencing
  5. Verify return tags: Confirm all relationships are bidirectional
  6. Add x-default: Set fallback for each page set
  7. 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.
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