What is x-default?

On a site in three languages, which version should be shown when a French-speaking user searches? The set does not answer that, because French is not in it. x-default fills the gap.

The value declares a role rather than a language. So the page it points to still carries its own language declaration separately — a page can be both “the Turkish version” and “the default”.

• There must be only one per set — two defaults create a contradiction.
• Optional — without it the engine makes its own decision.
• Not a redirect instruction — it addresses the search engine only.
• It can be the most widely reachable language, the main market’s language, or a language selection page.

The third item has an important consequence: a correctly configured x-default removes the need for automatic redirection. The search engine already shows the appropriate version.

On this site x-default points to the Turkish root, and the decision is a market preference — the target audience is centred on Türkiye. Every page carries four links: three languages and the default.

Which page is chosen is a strategic decision: the most widely reachable language, the main market’s language, or a language selection page. The third is neutral but adds friction and is usually unnecessary on small sites.

The larger the set, the harder the decision: on a site in seven languages no language is an obvious candidate for the default. At that scale either the most widely reachable language is chosen or a selection page is built.

The decision should be made once and documented with its reasoning — otherwise the argument over “which is the original version” reopens periodically within the team.

1. A role, not a language — the page pointed to declares its own language as well.
2. One per set — two defaults create a contradiction.
3. Not a redirect instruction — it addresses the search engine only.
4. Optional — without it the engine makes its own decision.
5. Declared in the page and the sitemap together — each is the other’s safeguard.

A note on verification: automated tools check that the declaration EXISTS, not whether it points to the right page. That is a strategic decision and only a human can verify it — which is why its reasoning has to be written down.

How to write it

The value is declared in the same place as the rest of the cluster: as link elements in the page head or in the sitemap. Every language version carries the same x-default line.

1. <link rel="alternate" hreflang="tr" href="https://www.example.com/">
2. <link rel="alternate" hreflang="en" href="https://www.example.com/en/">
3. <link rel="alternate" hreflang="x-default" href="https://www.example.com/">

Common mistakes

• Pointing x-default at a page that redirects visitors by language — that address never returns a stable page.
• Putting the line on one version only — every member of the cluster must carry the same declarations, x-default included, reciprocally.
• Pointing the default at a page excluded from the index — the target must be indexable.

You can check your tags before they go live with the hreflang validator: it reads the language links in pasted markup and flags the six most common mistakes.

The declaration itself is one member of the hreflang set; if the set is incomplete, x-default on its own says nothing.

We audit a multilingual site’s hreflang cluster and canonicals as part of SEO consulting; if the site has to be built in the target market’s language from the start, our B2B websites service is designed for exactly that.