Validates sitemap.xml, sitemap-image.xml, sitemap-news.xml + sitemap-index. Probes every URL for status, finds stale lastmod, dead URLs, missing image refs.
Tries /sitemap.xml by default. If you paste a full URL it uses that. Auto-discovers child sitemaps from a sitemap-index. HEAD-probes the first 50 URLs for status. Flags stale lastmod (older than 90d), 4xx URLs, redirect chains, and missing image refs.