Hreflang Tag Validator: Find Hreflang Errors Fast

Hreflang tags tell search engines which language and regional version of a page to show a given visitor. They are simple in theory and notoriously easy to get wrong in practice: a typo in a language code, a duplicate value, or a forgotten fallback can quietly send the wrong version of a page to an entire market. This tool parses the link tags you paste and checks each one for the mistakes that cause hreflang setups to fail silently.

What this validator checks

For every <link rel="alternate" hreflang="..."> tag found, the tool checks the language portion of the hreflang value against the ISO 639-1 list of two-letter language codes, checks that any region portion after a hyphen is a two-letter format, confirms the href is an absolute URL rather than a relative path, and flags any hreflang value that appears more than once in the set. It also notes whether an x-default tag is present.

Mistakes this catches

The most common hreflang errors are a language code that does not exist (a typo like "eng" instead of "en"), the same hreflang value used on two different URLs (which creates ambiguity about which one is correct), a relative href that will not resolve the same way on every page that includes it, and a missing x-default tag, which is not required by Google but is the recommended fallback for visitors whose language or region does not match any of your listed alternates.

What this validator does not check

This tool checks the tags as a set, in isolation. It cannot verify that the hreflang tags are reciprocal, meaning every page in the set links back to every other page in the set, since that requires crawling each URL. It also cannot confirm the destination pages actually load or return a 200 status. Full reciprocity and live URL checks are part of a complete technical SEO audit.