llms.txt

How is an llms.txt file structured?

The proposal defines a fixed order. The only required element is an H1 heading with the name of the site or project. It can be followed by a short summary in a blockquote, further paragraphs with details, and sections under H2 headings that contain lists of Markdown links, each with an optional note. By convention, a section named “Optional” holds secondary links an agent can skip when it needs a shorter context.

The proposal also suggests offering clean Markdown versions of important pages, either with .md appended (page.html.md) or with .md replacing the file extension. Version 2 adds link relations so agents can find them: rel="alternate" type="text/markdown" for the Markdown version and rel="describedby" for the applicable llms.txt, as HTML <link> elements or HTTP Link headers. The file can sit in a subdirectory, for example /docs/llms.txt, and then covers the URLs below that path. Where several files apply, the most specific one wins.

llms.txt does not control access. Crawling permissions stay with robots.txt, and sitemap.xml remains the complete list of URLs. llms.txt is a curated reading list on top of both.

Example

# Example Running Co.

> Maker of running shoes. The site has product specs, size charts and care guides.

## Products
- [Running shoes](https://www.example.com/running-shoes.md): all models with technical data
- [Size chart](https://www.example.com/sizes.md): US, UK and EU conversion

## Optional
- [Company history](https://www.example.com/about.md)

Does Google use llms.txt?

No. In its guide to generative AI features, Google says that machine-readable AI text files are not needed to appear in Google Search and that such files neither help nor harm a site’s visibility or rankings.

Lighthouse includes an llms.txt audit in its Agentic Browsing category. It only flags a page when requesting the file returns a server error. A missing file (404) is marked as not applicable, because the file is optional.

FAQ

Is llms.txt actually used? According to reports, mostly by developer documentation sites, whose content is read by coding assistants and agents. For Google Search it has no effect. A measurable effect on mentions in AI answers has not been shown so far.

Is llms.txt mandatory? No. It is a voluntary proposal. Lighthouse explicitly treats a missing file as not applicable.

What is llms-full.txt? A common variant that bundles the full text of a site or its documentation into one Markdown file. The proposal on llmstxt.org does not define it, in version 2 either.

Last updated: October 8, 2026