Hreflang Tags
Why it matters
Hreflang tags tell Google which version of a page to serve to users in different languages or regions. They solve the problem of international sites sending the wrong content to the wrong audience. When they are wrong, they are often silently wrong — the site works, Google crawls it, and the wrong pages rank in the wrong countries.
A UK site with a US version needs Google to show the US version to American searchers and the UK version to British ones. Without hreflang tags, Google makes its own determination based on domain, server location, and content language. It gets this right some of the time.
Where hreflang becomes necessary is multilingual sites or sites with regional pricing differences. A user landing on a page in the wrong currency or language has a worse experience, a lower conversion rate, and may not return.
Hreflang attributes must be consistent. Every page in a set must reference every other page in the set. A one-way reference — A referencing B but B not referencing A — invalidates both tags. Errors compound across large sites.
How we check it
We read every <link rel="alternate" hreflang="..."> element from the rendered page and record the set of language and region codes present. We store the full set as a snapshot.
If the set changes between crawls — a tag disappears, a region code changes, or new alternates appear — we flag it with before/after values. Hreflang errors are often introduced by CMS updates that modify template-level tags, so catching the change quickly allows you to fix it before international rankings are affected.
What to watch for
A hreflang tag disappearing for a specific region is the most common alert. Check your site template, your sitemap (which can also carry hreflang data), and any recently deployed CMS changes.
If hreflang tags are wrong for one page, they are probably wrong for all pages sharing the same template. Check canonical tags at the same time — canonical and hreflang interactions are a common source of confusion and indexing problems.