45.8% of llms.txt Files on Top Websites Come From Platforms That Publish One by Default

Summary

Picture a shop owner who gets an email from a consultant offering to "set up llms.txt" for a fee. She opens her store's address with /llms.txt on the end and finds a file already there. She never asked for it.

That is common. llms.txt is a short file that summarizes a site for AI tools, and several hosted store and site builders now publish one for every customer by default. Others leave it to the owner or to plugins.

We traced where the 110,188 llms.txt files on top-1M homepages come from. 45.8% sit on platforms that add the file for nearly every site. WordPress is the next biggest source, and there the file is much more common on sites that run a major SEO plugin.

What we measured

We used the HTTP Archive October 2026 mobile crawl (httparchive.crawl.pages), limited to top-1M homepages, and counted sites where /llms.txt returned 200 as text/plain or text/markdown. Each site gets one primary platform from HTTP Archive's technology detection.

We call a platform auto-publishing when 95% or more of its homepages in the sample serve the file. For WordPress we also checked which SEO plugins HTTP Archive detected. Detection shows a plugin is installed, not that it created the file.

Nearly half of all llms.txt files are platform defaults

Platform names appear here only as adoption facts.

Owners on these platforms likely did nothing to get the file. That makes it a default setting rather than a choice, and the content likely reflects the platform's template.

On WordPress, SEO plugins line up with the file

Plugin presence and the file coincide. Our data cannot show which plugin, if any, wrote a given file.

WordPress sites without a major SEO plugin have the file 6.8% of the time. With one of the plugins installed, the rate rises to between 17.0% and 42.1%.

The biggest sites do not rely on platform defaults

We split files by popularity rank and by whether they sit on an auto-publishing platform.

In the top 10,000, 630 of 662 files (95.2%) sit outside the auto-publishing platforms. Below rank 100,000, platform defaults make up 44.2% to 49.6% of all files.

What this means

Before paying anyone to create llms.txt, check whether your platform already did. If it did, your job is to review it: does it point to your best pages, and does it describe your business the way you would? If you run WordPress, your SEO plugin may have a setting for it that you can switch on and edit. Once it is accurate, move on, because the rest of SEO for AI search happens on your actual pages.

A default file is a starting point, not a finished one. The value comes from the choices inside it: which pages you list and how you describe them. Whether those choices help is easy to test: a free AI SEO audit shows if AI assistants can find and quote your business right now.

Limits

Platform and plugin detection come from HTTP Archive fingerprints and miss some sites.

An installed SEO plugin does not prove the plugin generated the file. We report the overlap only.

'Auto-publishing' is our label for platforms where at least 95% of sampled homepages serve the file; it is inferred from the data, not from platform documentation.

We did not inspect file contents, so we cannot say how much owners edited default files.

Frequently asked questions

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