What hreflang does, and why it's so easy to get wrong
Getting hreflang right is one of the trickiest parts of international SEO, one wrong code, a missing return tag or a non-absolute URL and Google quietly ignores the whole cluster. This tool does both halves of the job. The generator builds correct rel="alternate" hreflang annotations for every language and region version of a page, as HTML tags, XML sitemap markup or an HTTP Link header, with ISO 639-1 and 3166-1 codes validated as you type. The validator fetches any live URL (or your pasted HTML) and audits its hreflang setup, flagging invalid codes, missing x-default, absent self-references and, with deep validation, non-reciprocal return tags by actually crawling the alternates.
The hreflang attribute tells search engines which language and regional version of a page to show to which users, so a French speaker in Canada lands on your fr-CA page instead of the fr-FR or English one. It's powerful for international SEO, but unforgiving: the language must be a valid ISO 639-1 code, the optional region a valid ISO 3166-1 Alpha-2 code, every URL must be absolute, each page must reference every version including itself, and, crucially, the references must be reciprocal, if page A points to page B, page B must point back to A. Miss any of these and Google treats the annotations as unreliable and ignores them, which is why 'no return tags' is one of the most common Search Console warnings. This tool exists to make both building and checking hreflang foolproof.
