Sitemap Glossary

What is Sitemap Index?

An XML file that references multiple sitemap files, used when a site has too many URLs for a single sitemap.

Written by SitemapKit Editorial TeamUpdated: Jul 21, 2026

Key takeaways

Interpret Sitemap Index in its sitemap XML context; the detailed definition below explains its role and constraints.
Validate Sitemap Index against a real XML example instead of relying on the field or tag name alone.

A sitemap index file is an XML file that acts as a directory for multiple sitemap files. Since a single sitemap can contain a maximum of 50,000 URLs and must be under 50MB, large websites split their URLs across multiple sitemaps and reference them all from a sitemap index.

The sitemap index uses a `<sitemapindex>` root element containing `<sitemap>` entries, each with a `<loc>` pointing to an individual sitemap file and an optional `<lastmod>` date.

Search engines follow the sitemap index to discover and process all child sitemaps. Many CMS platforms (WordPress, Shopify) automatically generate sitemap indexes when the URL count exceeds the limit.

XML example

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <sitemap>
    <loc>https://example.com/sitemap-posts.xml</loc>
    <lastmod>2025-03-01</lastmod>
  </sitemap>
  <sitemap>
    <loc>https://example.com/sitemap-products.xml</loc>
    <lastmod>2025-02-28</lastmod>
  </sitemap>
</sitemapindex>

Continue with SitemapKit

Check an XML sitemap

Inspect Sitemap Index in a real sitemap.

Extract sitemap URLs

Turn XML sitemap fields into structured, exportable URL data.

API documentation

See how this concept appears in SitemapKit API responses.

Practical sitemap workflows

Apply sitemap concepts to SEO, monitoring, and data pipelines.

Sources and further reading

Work with sitemaps programmatically

SitemapKit's API discovers and parses XML sitemaps into structured JSON, including fields such as Sitemap Index.

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