# Hreflang / i18n _Source: https://seomatrix.ai/tools/hreflang/_ --- ## What it does Hreflang is an HTML annotation that tells search engines which language and regional version of a page to serve to each user; this checker validates that those annotations are complete and consistent across every version. It flags three failure modes that break multilingual indexing — a missing self-reference, duplicate or conflicting entries, and non-reciprocal (one-way) links — plus a missing x-default fallback, an optional but recommended safeguard. Broken hreflang makes engines serve the wrong language version or ignore your alternates entirely, surfacing the wrong page to searchers and to AI answer engines that cite by URL. ## What it checks - **Self-reference** — Every page in a hreflang set must list itself among the alternates; without this self-referencing tag search engines treat the annotation as unverified and may discard the whole cluster. - **x-default fallback** — The x-default value marks the page shown when no language or region matches the user's settings; it is optional but stops unmatched visitors from landing on the wrong locale. - **Reciprocity** — Hreflang links must be mutual — if page A points to page B, page B must point back to A; one-way links are treated as errors and dropped. - **Duplicate entries** — Two hreflang tags declaring the same language-region code with different URLs create a conflict engines cannot resolve, so neither URL is trusted. - **Language-region codes** — Values must be valid ISO 639-1 language codes, optionally with an ISO 3166-1 region (e.g. en, en-GB); a misspelled or non-existent code is silently ignored. - **Complete alternate set** — Each page should list the full set of every language version; if one version is omitted, the link between locales breaks and coverage is incomplete. ## How to use it 1. Paste the URL of one language version of your page into the checker. 2. Review the flagged issues — missing self-reference, absent x-default, duplicates, or one-way links — grouped by locale. 3. Fix the broken tags in each page's head (or sitemap / HTTP header) so every version lists the full, reciprocal set, then re-check. ## FAQ ### What is hreflang and when do I need it? Hreflang is an annotation that tells search engines the language and region a page targets. You need it whenever the same content exists in more than one language or regional variant, so engines serve the right version to each user. ### Does hreflang have to be reciprocal? Yes. Every alternate you declare must declare you back — non-reciprocal (one-way) hreflang is treated as an error and ignored by Google. ### What does x-default do? x-default names the fallback page for users whose language or region matches none of your alternates. It is optional but recommended, and usually points to a language selector or your default-language homepage. ### Where should hreflang tags go? In the of each page, in an XML sitemap, or in the HTTP header. Pick one method and apply it consistently — mixing methods for the same page can cause conflicts.