Hreflang for DACH: AI Platforms Ignore Language Signals
Hreflang signals "no longer function as hard constraints" in AI-mediated retrieval. Glenn Gabe's tests (December 2025) across ChatGPT, Perplexity, Gemini, Copilot and Claude found that AI platforms frequently deliver wrong language versions. 67 percent of domains have at least one hreflang issue.
Key Takeaways
- ✓AI platforms frequently deliver incorrect language versions (Glenn Gabe, Dec 2025)
- ✓67% of domains have at least one hreflang issue (Ahrefs, 374,756 domains)
- ✓Most common errors: Missing x-default (56.3%), missing self-referencing tags (18%)
- ✓Bing does NOT support hreflang — uses content-language meta tag instead
- ✓DACH minimum: de-DE, de-AT, de-CH, x-default with reciprocal tags
- ✓Subfolder approach (example.com/de/) preferred for domain authority consolidation
- ✓Picodi: 841% visibility increase after migration from 23 ccTLDs to one .com
Hreflang remains essential for traditional SEO — but AI platforms largely ignore it.
The AI-Hreflang Problem
Glenn Gabe's comprehensive tests in December 2025 across ChatGPT, Perplexity, Gemini, Copilot and Claude found that AI search platforms "frequently deliver wrong language versions." ChatGPT regularly served US-English URLs for French or Spanish queries. Advanced Web Rankings analysis confirms: Hreflang signals "no longer function as hard constraints" in AI-mediated retrieval.
Hreflang Problems in Practice
Ahrefs study of 374,756 domains: 67 percent have at least one hreflang issue. Most common errors: Missing x-default (56.3 percent), missing self-referencing tags (18 percent), links to broken/redirected pages (16.9 percent).
DACH-Specific
Minimal tags: de-DE, de-AT, de-CH and x-default, with reciprocal tags across all variants. Bing doesn't support hreflang — implement content-language meta tag, HTML lang attributes and TLD signals instead.
Subfolder vs. ccTLD
The trend is toward hybrid: Subfolders for content consolidation, ccTLDs for flagship markets. Picodi achieved 841 percent visibility increase after migrating from 23 ccTLDs to one .com with subfolders.
Data & Statistics
67% der Domains haben mindestens ein Hreflang-Problem
Ahrefs (374.756 Domains) (2025)Fehlendes x-default ist der häufigste Fehler (56,3% der betroffenen Sites)
Ahrefs (2025)Picodi: 841% Sichtbarkeitssteigerung nach Migration von 23 ccTLDs zu .com
SearchVIU Case Study (2025)“Hreflang is one of the most complex aspects of SEO. If you get it wrong, it can cause more problems than not having it at all.”
— John Mueller, Google Search Advocate