What hreflang does
hreflang annotations tell search engines that several URLs are versions of the same page in different languages or for different regions. Google then shows the German speaker your German page and the English speaker your English page, instead of whichever version happens to rank. For European firms that publish in a national language plus English, or serve several countries, this is one of the most important technical SEO details.
Annotations can be placed as link elements in the HTML head, in HTTP headers or in the XML sitemap. Each version must list all versions, including itself, and every target must link back. The checker reads the link elements in the page you enter; run it on each language version to confirm the return links.
What we check
- Language codes in ISO 639-1 format (de, fr, en) with optional ISO 3166-1 region codes (de-AT, fr-BE, en-GB).
- A self-referencing annotation for the page you enter.
- Absolute alternate URLs, and no language code listed twice.
- Whether an x-default entry is present for visitors whose language you do not serve.
- The lang attribute on the html element, and the canonical tag, which must not point every language to one version.
- All annotations listed in the report, so you can confirm each alternate URL and check its return link.
Frequent mistakes
The most common errors are missing return links, which make Google ignore the pair, and invalid codes such as en-UK instead of en-GB or using a country code alone. Others are pointing hreflang at the homepage of each language instead of the equivalent page, and canonical tags that all point to one language, which cancels the annotations.
Region codes are optional. Use them only if content really differs by country, for example different fees or legal frameworks for Austria and Germany; otherwise a plain language code is cleaner. Machine-translated pages with little review can be indexed, but they rarely win clients — translate the pages that matter carefully.
Choosing a URL structure
Language versions are usually served from subfolders such as /de/ and /en/, from subdomains or from separate country domains. Subfolders are the simplest to maintain and keep all authority on one domain. Whatever you choose, keep the structure parallel, so that each page has an obvious equivalent in every language, and translate titles and descriptions as well as the body text.