In short. Google supports cross-site sitemap hosting through verified ownership of all covered sites in Search Console or separate per-site sitemaps referenced in robots.txt.
Definition: A sitemap lists page URLs for search engines. Cross-site sitemap hosting stores sitemap files for several websites at a shared location, with authorization established through site ownership verification or references in each website's robots.txt file.
Key facts
- As of 17 October 2026, Google's sitemap construction documentation supports a shared hosting location and requires verified ownership of every covered site for Search Console cross-submission.
- The Sitemaps protocol treats control of a website's robots.txt file as evidence of authority to reference an externally hosted sitemap for that website.
- Google's robots.txt specification accepts a fully qualified sitemap URL on another host.
- Google's sitemap index documentation normally requires referenced sitemaps to share the index file's site, with an exception for configured cross-site submission.
What does Search Console submission require?
Google's cross-submission instructions require verified ownership of all websites whose URLs appear in the submitted files.
This route supports a combined sitemap containing URLs from different domains. It also supports separate files for each website, all stored at the shared location. Google's example places files such as host1-example-sitemap.xml and host2-example-sitemap.xml on https://host1.example.com.
A sitemap index is a file that lists sitemap files. The same instructions allow submission of the sitemaps themselves or a sitemap index through Search Console.
How does robots.txt authorize an external sitemap?
A robots.txt file provides crawler instructions for a website. The Sitemaps protocol's cross-submission rules explain that modifying this file demonstrates authority over the website. Its external sitemap reference expresses trust in that sitemap's contents.
For this route, Google's construction documentation requires separate sitemaps for each website, containing only that website's URLs. All files go on a site under the operator's control. Each covered website's own robots.txt points to its corresponding file.
For example, Google's construction guide places this reference in https://example.com/robots.txt:
sitemap: https://sitemaps.example.com/sitemap-example-com.xml
Google's robots.txt specification requires the complete URL, including protocol and host. The field applies independently of user-agent groups. Its name is case-insensitive; the URL value is case-sensitive.
How should the shared files be organized?
The Sitemaps protocol specifies UTF-8 encoding. Google's construction guide requires absolute page URLs and limits each sitemap to 50,000 URLs or 50 MB uncompressed; larger collections require multiple files.
Google's sitemap index rules require referenced files to sit in the index file's directory or deeper in the hierarchy. An index at /public/sitemap_index.xml, for example, can reference files under /public/shared/. The same documentation waives the same-site requirement when cross-site submission is configured.
Related terms
FAQ
Can I combine URLs from different domains in one file?
Yes. Google's Search Console cross-submission route permits this when you have verified ownership of all covered sites. Its robots.txt route requires files containing URLs from each individual site separately.
Which website needs the robots.txt reference?
Each website whose pages you submit needs its own reference. The Sitemaps protocol expects the URLs in the referenced sitemap to belong to the host whose robots.txt points to it.
Sources
- Google Search Central, "Build and submit a sitemap", 8 July 2026
- Sitemaps.org, "Sitemaps XML format", 21 November 2016
- Google Search Central, "How Google interprets the robots.txt specification", 31 August 2026
- Google Search Central, "Manage your sitemaps with a sitemap index file", 10 December 2025
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