Hreflang-Validator

It reads the hreflang tags in the page head, validates every language and region code, flags relative URLs, duplicate or conflicting codes, a missing self-reference or x-default, and canonical conflicts. It then loads each alternate URL to confirm it responds, links back, is indexable, and canonicalizes to itself.

Hreflang must be reciprocal. If your English page lists a French alternate, the French page must list the English page too. When the return tag is missing, search engines may ignore both annotations.

Yes. Each language version should canonicalize to itself. If the French page canonicalizes to the English page, you are telling search engines the French page is a duplicate, and its hreflang annotation is ignored.

The most common conflicts are one language code pointing to several URLs, country codes used as language codes (such as jp instead of ja, or en-uk instead of en-gb), alternates that redirect or return errors, and pages that list a different set of language versions.

It is recommended. x-default tells search engines which page to show visitors whose language or region you do not target, often a language picker or your main language version.

This tool checks hreflang tags in the HTML head, which is the most common implementation. If you declare hreflang in a sitemap instead, use the hreflang sitemap generator to rebuild it from a known-good set.