A broken or empty sitemap.xml quietly hurts how well search engines crawl your site. This free validator fetches yours, confirms it's valid XML, and counts the URLs it lists.
That the file is reachable (not a 404 or 500), is valid XML (a single stray character breaks the whole thing for crawlers), and actually lists URLs rather than being empty.
Use the box above, or the API: GET /sitemap?url=https://your-site.com.