The short version
A sitemap checker finds a website's XML sitemaps, validates that they parse, follows any sitemap index files to their children, and counts the URLs inside. Its practical value is catching the silent failures: a sitemap that returns HTML instead of XML, one that lists dead pages, or one that robots.txt never declares.
Where sitemaps actually live
There is a convention, and then there is what sites really do. The convention is a file at the root called sitemap.xml, plus a Sitemap line in robots.txt pointing at it.
In practice sitemaps turn up at sitemap_index.xml, at wp-sitemap.xml on modern WordPress, at sitemap-pages.xml alongside several siblings, and at paths a plugin invented years ago and nobody documented. Sites frequently have more than one, and often one nobody remembers publishing that is still being crawled.
This is why a checker looks in several places rather than one. Finding a forgotten sitemap listing three hundred URLs you deleted in 2023 is a common and useful outcome.
- /sitemap.xml, the convention
- /sitemap_index.xml, common on WordPress with an SEO plugin
- /wp-sitemap.xml, WordPress core since 5.5
- The Sitemap directive in /robots.txt, which may point somewhere unexpected
- Child sitemaps referenced inside a sitemap index
The failures that matter
Most sitemap validators report a long list of warnings that change nothing. A handful of problems genuinely cost you crawling, and they are worth separating from the noise.
The worst is a sitemap that is not XML. A misconfigured server or a deleted plugin leaves the URL returning an HTML error page with a 200 status, so nothing looks broken and the file is useless. This is silent and can persist for years.
Next is a sitemap listing URLs that redirect or 404. Search engines treat a sitemap as your own statement about which pages matter, and filling it with dead entries wastes crawl budget and undermines that signal.
Then there is the mismatch: pages that exist and matter but are absent from any sitemap, which is exactly the problem venbit.ai had until recently, with over two hundred pages reachable only through the sitemap and no internal links pointing at them.
What a sitemap does and does not do
A sitemap is a hint, not an instruction. It tells a search engine which URLs you consider canonical and worth crawling. It does not force indexing, it does not improve rankings by itself, and a page in a sitemap with no internal links pointing at it is still a page your own site is treating as unimportant.
The priority and changefreq attributes are largely ignored. Google has said as much. Filling them in carefully is harmless and mostly pointless.
What a sitemap genuinely helps with is discovery on large sites, on sites with weak internal linking, and for new pages you want found quickly. If your site is small and well linked, the sitemap is doing very little work, which is fine.
A short sitemap checklist
Run the tool above and then check five things, in this order.
Does every sitemap you can find return valid XML with a 200 status. Does robots.txt declare them. Does the URL count roughly match the number of pages you believe you have, because a large gap in either direction is informative. Do the listed URLs return 200 rather than redirects or errors. And are your important pages actually in there.
If the count is far higher than expected, you probably have old content or parameter URLs being published. If it is far lower, something is filtering pages out, usually a plugin setting or a noindex tag.
Reading the results
The checker reports a handful of states. Here is what each one actually means for you, and how urgent it is.
| What you see | What it means | How urgent |
|---|---|---|
| Not valid sitemap XML | The URL returns something, usually an HTML error page, with a 200 status. Crawlers get nothing | Fix now. This is invisible and total |
| No sitemap found at all | Discovery depends entirely on your internal links | Fix soon on a large site, low priority on a small well-linked one |
| Exists but not in robots.txt | Search engines have to guess the location | Low. One line in robots.txt |
| Several sitemaps responding | Normal, but check none are forgotten leftovers | Worth ten minutes |
| URL count far off what you expect | Either old content is being published or pages are being filtered out | Investigate, it usually reveals a real problem |
Questions about this tool
What does this checker look for?+
It looks at the conventional locations, reads the Sitemap directives in robots.txt, follows any sitemap index files to their children, then validates that each one parses as XML and counts the URLs.
Does a sitemap improve my rankings?+
Not directly. It helps search engines discover URLs, which matters most on large sites, on sites with poor internal linking, and for new pages. A well-linked small site gets little benefit from one.
Do priority and changefreq matter?+
Very little. Google has indicated it largely ignores them. Setting them carefully is harmless but not worth much effort.
My sitemap URL loads in a browser but the tool says it is invalid. Why?+
Usually because it is returning HTML rather than XML, often an error page served with a 200 status. It looks fine to a human and is useless to a crawler. This is the most common silent sitemap failure.
Should every page be in my sitemap?+
Every page you want indexed, yes. Pages you deliberately exclude from search, no. And a page in your sitemap with no internal links pointing at it is a signal problem worth fixing separately.