What date format does lastmod need?

W3C datetime: 2026-09-10, or with a time and offset such as 2026-09-10T14:30:00+01:00. Other formats are ignored, so the sitemap reports no change dates at all.

How many URLs can one sitemap hold?

50,000, and 50 MB uncompressed. Past either limit, split the file and reference the parts from a sitemap index.

Do priority and changefreq do anything?

Very little. Google ignores priority and largely ignores changefreq, using what it observes about the page instead. They are harmless but not worth maintaining.

Sitemap Validator

Check an XML sitemap for structural errors, bad dates, wrong hosts and the published limits.

Runs in your browserNo account neededFree

Processing: This tool runs entirely in your browser. Your input and any file you open stay on your device — nothing is uploaded to a server.

How to use the sitemap validator

Paste the contents of sitemap.xml or a sitemap index.
Read the errors first, then the warnings.
Check the entry table for the URLs that failed.

About this tool

Three rules account for most broken sitemaps, and none of them announces itself when broken.

Every `<loc>` must be an absolute URL on the same host the sitemap is served from — a relative path is dropped, and a URL on another host is ignored entirely, so a sitemap that lists a staging domain silently submits nothing. `<lastmod>` must be a W3C datetime: `2026-09-10` and `2026-09-10T14:30:00+01:00` are valid, while `10/09/2026` is not a date as far as the protocol is concerned, which means a sitemap can look diligently maintained while telling a crawler nothing about when anything changed. And one file may hold 50,000 URLs and 50 MB uncompressed; beyond either limit, split it and list the parts in a sitemap index.

The checker also reports what is *pointless* rather than wrong, because that is where most sitemap effort goes. Google ignores `priority` outright and largely ignores `changefreq`, preferring what it observes about how often a page actually changes. Neither does harm; both are work spent on nothing, and a sitemap where every URL has priority 0.8 is a sitemap that has said nothing at all.

Both sitemaps and sitemap indexes are recognised, and malformed XML is reported with the position of the fault rather than a generic failure.

Common uses

Checking a generated sitemap before submitting it.
Working out why Search Console rejected a sitemap.
Auditing lastmod dates that a crawler may be ignoring.

Frequently asked questions

What date format does lastmod need?: W3C datetime: 2026-09-10, or with a time and offset such as 2026-09-10T14:30:00+01:00. Other formats are ignored, so the sitemap reports no change dates at all.
How many URLs can one sitemap hold?: 50,000, and 50 MB uncompressed. Past either limit, split the file and reference the parts from a sitemap index.
Do priority and changefreq do anything?: Very little. Google ignores priority and largely ignores changefreq, using what it observes about the page instead. They are harmless but not worth maintaining.

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