llms.txt

A proposed standard file at /llms.txt that helps AI language models understand a site's content structure and guidelines.

llms.txt is a proposed open standard (analogous to robots.txt but for large language models) introduced by Jeremy Howard in September 2024. The file, placed at the root of a domain (/llms.txt), provides a plain-text overview of the site's content hierarchy in Markdown format — designed to be consumed by AI systems when they need to understand a site's structure and important content.

The specification includes two files: /llms.txt (brief overview with links to key documentation) and /llms-full.txt (complete documentation in a single file for AI context windows). The format lists key sections as H2 headings with brief descriptions and links to the most important pages in each section.

Adoption is growing: Anthropic, Perplexity, Cloudflare, Shopify, and thousands of other sites have implemented llms.txt. Whether major AI engines use it as a formal indexing signal is still evolving, but its presence signals AI-readiness and is recommended as part of any GEO strategy.