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Fetch one public page and review its HTML hreflang tags for supported code patterns, absolute URLs, duplicates, self-reference, and optional x-default.
> Target_URL
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Extract hreflang alternate links from the fetched HTML for one public page.
Check language values against the tool's supported syntax pattern; unusual codes need source verification.
Find repeated hreflang values on the submitted page for manual review.
Report whether the page declares a fallback for unmatched language settings.
Check for fully qualified href values and an entry that references the submitted URL.
Distinguish a single-page HTML check from return-link, HTTP-header, and sitemap testing.
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The Hreflang Tester fetches any public URL and extracts all <link rel="alternate" hreflang="..."> tags from the fetched HTML. It applies a supported language-tag syntax pattern, checks for absolute href values, duplicate language entries, and a self-reference, and reports whether it found an optional x-default fallback tag. It does not fetch alternate URLs, test return links, or inspect HTTP-header and sitemap implementations.
Google supports a language code and, optionally, a region or script in hreflang values. Common supported formats include en (English), en-US (English, United States), zh-Hans (Simplified Chinese), and pt-BR (Portuguese, Brazil). Invalid codes like english or en_US(underscore instead of hyphen) need correction. This tool uses a syntax pattern rather than the complete language-subtag registry, so verify flagged or unusual codes against Google's current supported-code guidance.
The most frequent hreflang errors are using relative URLs instead of absolute URLs in the href attribute, duplicating a target on one page, using unsupported language or region codes, and omitting a self-reference. Return links also matter: localized equivalents should point back to each other. This single-page checker does not fetch those alternates, and x-default remains an optional fallback rather than a validity requirement.