What is an XML Sitemap?
An XML sitemap is a structured XML (Extensible Markup Language) document listing all the critical URLs of your website. Search engines read this file to discover new page locations, audit last modification dates, and understand the relative crawling priority of your page index structures.
Understanding Sitemap and Sitemap Index Tags
XML sitemaps must adhere to the schema declarations managed by Sitemaps.org:
- loc: The absolute URL of the page. Must start with the correct protocol prefix (
httporhttps). - lastmod: The ISO 8601 date when the page content was last modified (e.g.
2026-03-01). Tells crawlers if they need to re-index the page. - priority: A decimal value between
0.0and1.0suggesting crawl importance compared to other site pages. - Sitemap Index: A parent sitemap file listing child sitemap files. Essential for websites exceeding the single sitemap limit of 50,000 URLs or 50MB file size.
Why Validate Your XML Sitemaps?
Search engine crawlers are strict XML parsers. A single open bracket error, missing schema definition, or unescaped character (like an raw ampersand & instead of &) will cause the entire XML parsing to fail. An invalid sitemap prevents crawlers from scanning page links, blocking site indexing. Validating sitemaps client-side is a key pre-publication task.
Frequently Asked Questions
Q: Does my sitemap data upload to a server?
No. The validator runs entirely in your local browser sandbox using native DOM parsing APIs. Your sitemap URL lists and site structures remain private.
Q: What is the maximum size of a standard sitemap?
A single XML sitemap can contain up to 50,000 URLs and cannot exceed 50 Megabytes in uncompressed file size. If your site is larger, you must divide it and use a sitemap index file.