Seo Hreflang

Name: Seo Hreflang
Author: agricidaniel

agricidaniel/claude-seo

4k installs
12.5k repo stars
Updated July 27, 2026
agricidaniel/claude-seo

seo-hreflang is an agent skill that audits, validates, and generates hreflang tags for multi-language and multi-region SEO.

About

SEO Hreflang is an agent skill for international SEO that validates existing hreflang implementations or generates correct tags for multi-language and multi-region sites. It checks eight validation areas: self-referencing tags matching canonical URLs, bidirectional return tags across all alternates, required x-default fallback, ISO 639-1 language codes, ISO 3166-1 region qualifiers, canonical alignment, HTTPS protocol consistency, and cross-domain support with Search Console verification. Common mistakes are ranked by severity from missing self-ref or return tags through invalid eng or en-uk codes to trailing-slash mismatches. Implementation methods include HTML link tags for small sites, HTTP headers for non-HTML files, and XML sitemaps recommended for large or cross-domain setups with xmlns:xhtml entries on every url node. Generation workflow detects languages, maps page equivalents, validates codes, outputs tags, verifies return mesh, and adds x-default. Extended modules cover cultural adaptation scoring, content parity audits, and locale number or date format validation via on-demand reference files.

Eight validation checks cover self-ref, return tags, x-default, ISO codes, canonical, and HTTPS.
Supports HTML head tags, HTTP Link headers, and XML sitemap hreflang implementations.
Common mistakes table ranks missing self-ref and return tags as critical severity.
Generation workflow maps page equivalents and verifies full bidirectional alternate mesh.
Extended cultural adaptation, content parity, and locale format audits via reference files.

Seo Hreflang by the numbers

3,978 all-time installs (skills.sh)
+413 installs in the week ending Jul 28, 2026 (Skillselion tracking)
Ranked #173 of 1,881 Marketing & SEO skills by installs in the Skillselion catalog
Security screen: MEDIUM risk (skills.sh audit)
Data as of Jul 28, 2026 (Skillselion catalog sync)

At a glance

seo-hreflang capabilities & compatibility

Capabilities: self ref, return tag, and x default validation · iso 639 1 and iso 3166 1 code correction · html, http header, and xml sitemap generation · cross domain hreflang with search console guidan · cultural adaptation and content parity audit mod
Works with: google drive
Use cases: seo · web search

From the docs

What seo-hreflang says it does

Missing self-referencing tags cause Google to ignore the entire hreflang set

SKILL.md

npx skills add https://github.com/agricidaniel/claude-seo --skill seo-hreflang

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Last updated	July 27, 2026
Repository	agricidaniel/claude-seo ↗

How do I validate or implement hreflang tags with correct self-ref, return tags, x-default, and ISO language codes?

Audit, validate, and generate hreflang tags for multi-language sites with self-ref, return tags, x-default, and ISO code checks.

Who is it for?

SEO engineers auditing international sites or generating hreflang for new multilingual page sets.

Skip if: Skip when the site is single-language with no regional variants or alternate URLs to map.

When should I use this skill?

User mentions hreflang, i18n SEO, international SEO, multi-language tags, or language alternates.

What you get

Validation report with severity-ranked issues plus generated HTML, HTTP header, or sitemap hreflang implementations.

Content parity audit matrix
Per-locale SEO gap report

Files

SKILL.mdMarkdownGitHub ↗

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

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)

Cultural Adaptation Assessment

When analyzing a multi-language site, go beyond technical hreflang validation to assess whether the content is culturally adapted for each target market.

Load references/cultural-profiles.md for pre-built profiles (DACH, Francophone, Hispanic, Japanese).

Assessment steps: 1. Identify all language versions and their target markets 2. Load the relevant cultural profile(s) 3. Check CTAs match cultural expectations (direct vs indirect) 4. Check trust signals are locale-appropriate (certifications, legal pages) 5. Check for foreign brand references on localized pages 6. Check number/date/currency formatting consistency 7. Flag cultural adaptation issues as Medium severity

Output: Cultural Adaptation Score per language version (0-100) with specific findings.

Content Parity Audit

Command: /seo hreflang audit <directory-or-url>

Audit content parity across all language versions of a site or local content directory.

Load references/content-parity.md for the full parity matrix and scoring methodology.

What it checks:

Page existence across all declared languages
Section structure equivalence (H2/H3 count)
SEO element parity (title, meta, schema localization)
Word count ratio validation (DE should be 25-35% longer than EN, JA 10-25% shorter)
Freshness tracking (stale translations detected via timestamps)
Cultural marker scanning (foreign brands, wrong legal references, untranslated elements)

Output: Parity matrix table with per-page scores and prioritized action items.

Locale Format Validation

Load references/locale-formats.md for number, date, currency, address, and phone format reference tables per locale.

Checks:

Number format consistency (e.g., "1,000.00" should be "1.000,00" on de-DE pages)
Date format matches locale expectations
Currency symbols and placement correct for target market
Phone numbers use international format with correct country code

Reference Files

Load on-demand as needed (do NOT load all at startup):

references/cultural-profiles.md: DACH, Francophone, Hispanic, Japanese cultural adaptation profiles
references/locale-formats.md: Number, date, currency, address, phone format tables per locale
references/content-parity.md: Content parity audit methodology and scoring

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.
Cultural profile not available for language	Use the Default Profile checklist from cultural-profiles.md. Note that assessment is based on general guidelines, not a pre-built profile.
Content parity directory empty	Report that no content files were found. Suggest verifying the directory path or providing a URL for live site analysis.

Content Parity Audit for Multi-Language Sites

Load this reference when auditing content parity across language versions of a site. Content parity ensures all language versions provide equivalent value and SEO signals.

Original concept: Chris Muller (Pro Hub Challenge)

Content Parity Matrix

For each page that exists in multiple languages, check:

Dimension	What to Compare	Acceptable Variance	Severity if Failing
Page existence	Does equivalent page exist in all declared languages?	0% — all declared languages must have the page	High
Section structure	Same number of H2/H3 sections?	±1 section allowed	Medium
FAQ items	Same number of FAQ questions?	±2 items allowed	Medium
Images	Same number of images with localized alt text?	Must match exactly	Medium
Charts/SVGs	Charts present in all versions?	Must match exactly	Low
Word count	Proportional to language expansion ratio?	±30% of expected ratio	Low
Schema markup	JSON-LD present and localized in all versions?	Must match type and key properties	High
Title tag	Localized with target keyword in local language?	Must be localized, not English	High
Meta description	Localized and within character limits?	Must be localized	Medium

Freshness Tracking

Detect stale translations by comparing: 1. File modification timestamps: If EN version was updated after DE version, DE may be stale 2. Frontmatter dates: Compare date_modified or lastmod across language versions 3. Content hash comparison: If the source language content hash changed since last translation

Freshness delta thresholds:

Fresh: Translated within 7 days of source update → OK
Aging: 8-30 days since source update → Low priority update
Stale: 31-90 days since source update → Medium priority update
Outdated: 90+ days since source update → High priority update

Word Count Ratio Validation

Expected word count ratios vs English source:

Target Language	Expected Ratio	Acceptable Range
German (DE)	1.25-1.35x	1.10-1.50x
French (FR)	1.15-1.25x	1.00-1.40x
Spanish (ES)	1.15-1.25x	1.00-1.40x
Japanese (JA)	0.75-0.90x	0.60-1.00x
Chinese (ZH)	0.70-0.80x	0.55-0.95x

A German translation that is shorter than the English original likely has missing content. A Japanese translation that is longer than English likely has unnecessary padding.

Cultural Adaptation Quality Gates

Beyond direct translation, check for cultural markers that indicate proper localization:

Check	What to Look For	Severity
Foreign brand references	US-specific brands on non-US pages (e.g., "Walmart" on de-DE)	Medium
Foreign statistics	US-only data cited on localized pages (e.g., "80% of Americans")	Medium
CTA aggressiveness	Aggressive CTAs on formal-culture pages (e.g., "BUY NOW!" on ja-JP)	Low
Legal references	Wrong jurisdiction laws cited (e.g., CCPA on de-DE instead of DSGVO)	High
Currency/unit mismatch	USD prices on EUR pages, imperial units on metric pages	High
Untranslated elements	English text remaining in navigation, buttons, alt text, schema	Medium

Parity Score Calculation

Score out of 100:

Page existence parity: 30 points
SEO element parity (title, meta, schema): 30 points
Content structure parity (sections, images, FAQ): 25 points
Freshness parity: 15 points

Interpretation:

90-100: Excellent parity across all language versions
70-89: Good parity with minor gaps to address
50-69: Significant parity issues affecting some language versions
Below 50: Major parity failures requiring immediate attention

Output Format

Present as a matrix table:

| Page | EN | DE | FR | ES | JA | Parity Score |
|------|----|----|----|----|----| -------------|
| /about | ✅ | ✅ | ✅ | ❌ | ✅ | 80/100 |
| /pricing | ✅ | ✅ | ⚠️ | ❌ | ❌ | 45/100 |

Cultural Adaptation Profiles for International SEO

Load this reference when analyzing multi-language sites or generating hreflang implementations. Profiles guide cultural assessment beyond technical validation.

Original concept: Chris Muller (Pro Hub Challenge)

DACH Region (DE, AT, CH)

Dimension	Guideline
Formality	High. Use "Sie" (formal you). Professional tone expected.
Humor	Conservative. Avoid sarcasm and wordplay in CTAs.
CTA Style	Indirect preferred. "Jetzt entdecken" over "Jetzt kaufen".
Trust Signals	Certifications (TUV, ISO), "Datenschutz" (privacy), Impressum required by law.
Legal	Impressum page mandatory. DSGVO (GDPR). Widerrufsrecht (right of withdrawal).
Number Format	1.000,00 (dot for thousands, comma for decimal)
Date Format	DD.MM.YYYY
Currency	EUR (DE/AT), CHF (CH)
Color Symbolism	Blue = trust, Green = eco/nature, Red = caution (not urgency)
Brand Substitution	Walmart → MediaMarkt, Home Depot → Hornbach, Amazon → Otto/Zalando
Word Expansion	+25-35% vs English (plan for longer headlines and button text)

Francophone (FR, BE, CA-FR, CH-FR)

Dimension	Guideline
Formality	Medium-high. "Vous" default. "Tu" only for youth/casual brands.
Humor	Appreciated when sophisticated. Avoid blunt/direct humor.
CTA Style	Elegant phrasing. "Decouvrir nos solutions" over "Achetez maintenant".
Trust Signals	"Fabrique en France" (made in France), professional certifications, press mentions.
Legal	Mentions legales required. CNIL (data protection). CGV (terms).
Number Format	1 000,00 (space for thousands, comma for decimal)
Date Format	DD/MM/YYYY
Currency	EUR (FR/BE), CAD (CA-FR), CHF (CH-FR)
Color Symbolism	Blue = stability, White = purity/luxury, Red = passion
Brand Substitution	Walmart → Carrefour, Amazon → Fnac/Cdiscount, Target → Leclerc
Word Expansion	+15-25% vs English

Hispanic (ES, LATAM)

Dimension	Guideline
Formality	Varies by country. Spain: "Usted" formal. LATAM: mixed.
Humor	Warm and relational. Self-deprecating humor accepted.
CTA Style	Warm, personal. "Empieza tu viaje" over "Comprar ahora".
Trust Signals	Community proof, family/relationship themes, celebrity endorsements popular.
Legal	LOPD (Spain data protection). Each LATAM country has own regulations.
Number Format	Spain: 1.000,00 / LATAM: varies by country
Date Format	DD/MM/YYYY (most), DD-MM-YYYY (some LATAM)
Currency	EUR (ES), regional currencies (MXN, ARS, COP, CLP, PEN)
Color Symbolism	Red = energy/passion, Yellow = warmth, Blue = trust
Brand Substitution	Walmart → Mercadona (ES) / Coppel (MX), Amazon → MercadoLibre
Word Expansion	+15-25% vs English

Japanese (JA)

Dimension	Guideline
Formality	Very high. Keigo (honorific language) expected in business.
Humor	Subtle. Avoid direct humor in B2B. Kawaii (cute) elements acceptable in B2C.
CTA Style	Subtle and polite. "Otoiawase" (inquire) over direct "buy now".
Trust Signals	Company longevity, ISO certifications, endorsements from recognized institutions.
Legal	APPI (Act on Protection of Personal Information). Tokutei Shotorihiki law.
Number Format	1,000 (comma for thousands, no decimal in most contexts)
Date Format	YYYY/MM/DD or YYYY年MM月DD日
Currency	JPY (no decimals)
Color Symbolism	White = purity, Red = vitality/celebration, Black = formality
Brand Substitution	Amazon → Rakuten, Google Shopping → Yahoo! Shopping Japan
Word Contraction	-10-25% vs English (Japanese is more compact)

Default Profile (Unlisted Languages)

When analyzing a locale without a pre-built profile above:

1. Research formality norms: Check if the language has formal/informal registers (e.g., Korean has 7 speech levels) 2. Check text direction: LTR vs RTL (Arabic, Hebrew, Farsi, Urdu) 3. Verify number/date formats: Use CLDR (Unicode Common Locale Data Repository) 4. Research legal requirements: Privacy law, business registration, consumer protection 5. Check word expansion ratio: Germanic/Slavic languages expand, CJK languages contract 6. Verify currency and payment preferences: Local payment methods may need mention 7. Research color meanings: Colors have different cultural associations globally

How to Use in Analysis

When running /seo hreflang on a multi-language site: 1. Identify all language versions and their target markets 2. Load the relevant cultural profile(s) 3. Check that CTAs, trust signals, and legal pages match the cultural expectations 4. Flag mismatches as "Cultural Adaptation" findings (Medium severity) 5. Check number/date/currency formatting consistency within each locale version

Locale Format Reference for International SEO

Load this reference when validating content parity or generating localized content. Mismatched formats (e.g., US date format on a German page) signal poor localization and reduce user trust.

Original concept: Chris Muller (Pro Hub Challenge)

Number Formats

Locale	Thousands	Decimal	Example
en-US	,	.	1,234.56
en-GB	,	.	1,234.56
de-DE	.	,	1.234,56
de-AT	.	,	1.234,56
de-CH	'	.	1'234.56
fr-FR	(space)	,	1 234,56
fr-CA	(space)	,	1 234,56
es-ES	.	,	1.234,56
es-MX	,	.	1,234.56
ja-JP	,	.	1,234
pt-BR	.	,	1.234,56
it-IT	.	,	1.234,56
nl-NL	.	,	1.234,56
ko-KR	,	.	1,234
zh-CN	,	.	1,234.56

Date Formats

Locale	Format	Example
en-US	MM/DD/YYYY	04/14/2026
en-GB	DD/MM/YYYY	14/04/2026
de-DE	DD.MM.YYYY	14.04.2026
fr-FR	DD/MM/YYYY	14/04/2026
es-ES	DD/MM/YYYY	14/04/2026
ja-JP	YYYY/MM/DD or YYYY年MM月DD日	2026/04/14
pt-BR	DD/MM/YYYY	14/04/2026
ko-KR	YYYY.MM.DD	2026.04.14
zh-CN	YYYY年MM月DD日	2026年04月14日

Currency Formats

Locale	Symbol	Placement	Example
en-US	$	Before	$1,234.56
en-GB	£	Before	£1,234.56
de-DE	€	After (space)	1.234,56 €
fr-FR	€	After (space)	1 234,56 €
es-ES	€	After (space)	1.234,56 €
ja-JP	¥	Before	¥1,234
pt-BR	R$	Before	R$ 1.234,56
ko-KR	₩	Before	₩1,234
zh-CN	¥	Before	¥1,234.56
de-CH	CHF	Before	CHF 1'234.56

Address Formats

Region	Order	Example
US/CA	Street, City, State ZIP	123 Main St, Austin, TX 78701
UK	Street, City, Postcode	10 Downing St, London, SW1A 2AA
DE/AT	Street Nr, PLZ City	Hauptstr. 1, 10115 Berlin
FR	Street, Code Postal City	1 Rue de Rivoli, 75001 Paris
JP	Postal City District Street	〒100-0001 東京都千代田区千代田1-1

Phone Formats

Region	Format	Example
US	+1 (XXX) XXX-XXXX	+1 (512) 555-0123
UK	+44 XXXX XXXXXX	+44 2071 234567
DE	+49 XXX XXXXXXX	+49 30 12345678
FR	+33 X XX XX XX XX	+33 1 23 45 67 89
JP	+81 X-XXXX-XXXX	+81 3-1234-5678

Text Expansion Ratios (vs English)

Language	Expansion	Impact
German	+25-35%	Longer headlines, buttons, navigation labels
French	+15-25%	Moderate expansion
Spanish	+15-25%	Moderate expansion
Italian	+15-25%	Moderate expansion
Portuguese	+15-25%	Moderate expansion
Dutch	+10-20%	Slight expansion
Japanese	-10-25%	Contraction (more compact)
Korean	-10-20%	Contraction
Chinese	-20-30%	Significant contraction

Validation Rules

When checking locale format consistency: 1. Scan for number patterns on the page (prices, statistics, measurements) 2. Compare against the expected format for the page's declared language 3. Flag US-format numbers on non-US pages (e.g., "$1,234.56" on a de-DE page) 4. Check date formats in blog posts, copyright notices, update timestamps 5. Verify currency symbols match the target market 6. Check that phone numbers use international format with correct country code

Machine-translation QA flag (Jan 2025 QRG)

Google's January 23, 2025 Quality Rater Guidelines update added explicit language about machine-translated content with no human review as a form of scaled content abuse (§4.6.5).

"Using automated tools (generative AI or otherwise) as a low-effort

way to produce many pages that add little-to-no value."

Machine-translated content is fine when reviewed by a human speaker and corrected. Untranslated MT — or "lightly post-edited" output that still contains hallucinated terms, wrong gender/number agreement, or untranslated proper nouns — is treated as scaled content abuse.

Signals the seo-hreflang audit should surface

Signal	Severity	Notes
Multiple `hreflang` alternates point to URLs whose content is identical except for header chrome	Critical	Indicates the body wasn't translated; just template wrapped.
`lang="xx"` attribute on `<html>` doesn't match the body language	High	Translation pipeline output without a final QA step.
Auto-translated `<meta name="description">` longer than 160 chars (untrimmed)	Medium	The translator overran the snippet limit — no human reviewer caught it.
`lang` attribute is `auto` or missing entirely	Medium	Pages that don't declare their language confuse hreflang + AI crawlers.
Untranslated proper nouns or product names sprinkled in body	Low (heuristic)	Common MT failure mode; hard to detect automatically.
Schema.org `inLanguage` field absent or wrong	Medium	Multi-language audits should cross-check `inLanguage` vs. body.

What the audit should NOT flag

Sites that have a few MT pages clearly labelled as MT (a

human-translation-fallback pattern). Google's QRG explicitly permits MT when honestly labelled and clearly scoped.

Machine-translated UI strings — those are i18n, not "content".
Content with lang="auto" if the audit can't fetch a fallback

signal (be conservative; don't claim what we can't verify).

Cross-skill delegation

For per-page hreflang validation, stay inside seo-hreflang.
For broader scaled-content scoring (entropy of translated pages,

AI-pattern detection in body), defer to seo-content via python3 scripts/content_quality.py.

For "is this translated by Google's own auto-translate widget"

detection, look for the .goog-te-banner-frame iframe; auto- translate widgets are explicitly exempted from MT-scaled-content abuse but produce poor passage-citability anyway.

Primary sources

Jan 2025 QRG §4.6.5: https://services.google.com/fh/files/misc/hsw-sqrg.pdf
John Mueller on MT (multiple SOTR episodes, 2024-2025): MT is OK

when reviewed by a human; bulk MT without review is abuse.

Last verified: 2026-05-17.

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How it compares

Pick seo-hreflang when you need cross-locale content equivalence audits, not just hreflang tag syntax validation.

FAQ

What makes Google ignore an entire hreflang set?

Missing self-referencing tags where each page must include an hreflang pointing to its own canonical URL.

Which implementation method scales best?

XML sitemaps with xmlns:xhtml are recommended for large sites, cross-domain setups, or fifty plus variants per page.

What is a common invalid language code mistake?

Using eng instead of en or jp instead of ja; hreflang requires ISO 639-1 two-letter language codes.

Is Seo Hreflang safe to install?

skills.sh reports 2 of 3 security scanners passed. Review the Security Audits panel on this page before installing in production.

Marketing & SEOseo

About

Seo Hreflang by the numbers

seo-hreflang capabilities & compatibility

What seo-hreflang says it does

Add your badge

How do I validate or implement hreflang tags with correct self-ref, return tags, x-default, and ISO language codes?

Who is it for?

When should I use this skill?

What you get

Files

Hreflang & International SEO

Validation Checks

1. Self-Referencing Tags

2. Return Tags

3. x-default Tag

4. Language Code Validation

5. Region Code Validation

6. Canonical URL Alignment

7. Protocol Consistency

8. Cross-Domain Support

Common Mistakes

Implementation Methods

Method 1: HTML Link Tags

Method 2: HTTP Headers

Method 3: XML Sitemap (Recommended for large sites)

Method Comparison

Hreflang Generation

Process

Hreflang Sitemap Generation

Sitemap with Hreflang

Output

Hreflang Validation Report

Summary

Validation Results

Generated Hreflang Tags

Recommendations

Cultural Adaptation Assessment

Content Parity Audit

Locale Format Validation

Reference Files

Error Handling

Content Parity Audit for Multi-Language Sites

Content Parity Matrix

Freshness Tracking

Word Count Ratio Validation

Cultural Adaptation Quality Gates

Parity Score Calculation

Output Format

Cultural Adaptation Profiles for International SEO

DACH Region (DE, AT, CH)

Francophone (FR, BE, CA-FR, CH-FR)

Hispanic (ES, LATAM)

Japanese (JA)

Default Profile (Unlisted Languages)

How to Use in Analysis

Locale Format Reference for International SEO

Number Formats

Date Formats

Currency Formats

Address Formats

Phone Formats

Text Expansion Ratios (vs English)

Validation Rules

Machine-translation QA flag (Jan 2025 QRG)

Signals the seo-hreflang audit should surface

What the audit should NOT flag

Cross-skill delegation

Primary sources

Related skills

How it compares

FAQ

What makes Google ignore an entire hreflang set?

Which implementation method scales best?

What is a common invalid language code mistake?

Is Seo Hreflang safe to install?

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