Hreflang Auditor
Audit a set of hreflang annotations for missing return tags, invalid language and region codes, missing self-references and absent x-default, which are the four faults that break most implementations.
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Hreflang fails silently
An incorrect hreflang set produces no error, no warning and no visible change. The tags are simply ignored, and the wrong language version continues to rank in each market exactly as it did before. Because there is nothing to notice, broken implementations survive for years. The only way to know an implementation works is to audit the annotations themselves against the rules, which is what this does.
The return tag rule is the one that breaks
Every page in a set must point at every other page in that set, including itself, and each of those pages must point back. A one directional annotation is discarded entirely. This is why adding a new language to an existing set is the most common moment for a set to break: the new page lists all the others, and every existing page has to be updated to list the new one, which is easy to overlook when there are twelve of them.
Codes must be a language, optionally with a region
The value is an ISO 639-1 language code, optionally followed by an ISO 3166-1 Alpha 2 region code. A region alone is invalid, so a tag for the United Kingdom market must be en-GB rather than GB, and a tag written as en-UK is invalid because UK is not the ISO code for the United Kingdom, which is GB. These two mistakes account for a large share of every audit.
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Frequently Asked Questions
What is a return tag?
A pointer back. If page A declares page B as its Spanish version, page B must declare page A as its English version. Annotations that are not reciprocated are discarded entirely, which is why one sided sets do nothing at all.
Does a page need to reference itself?
Yes. Every page in the set must include a self referencing annotation with its own language and region. Sets missing self references are frequently ignored, and it is one of the simplest faults to introduce and to miss.
Why is en-UK invalid?
Because the region part uses ISO 3166-1 Alpha 2, where the United Kingdom is GB. UK is not a valid code in that standard, so en-UK is silently ignored while looking entirely reasonable.
Do I need x-default?
It is not required and it is strongly advisable. It tells search engines which page to show when no listed language matches the user, and without it those users are served whichever version the algorithm guesses.
Can hreflang and canonical conflict?
Yes, and it is a common way to break a set. Each language version must canonicalise to itself. Pointing several language versions at one canonical tells search engines they are duplicates, which contradicts the hreflang annotation and voids it.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Paste your hreflang tags grouped by page to find the errors that stop them working.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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