llms.txt is a proposed convention: a plain-text file at /llms.txt that tells AI crawlers what your site is about and which pages matter, written in a simple markdown-like format that models can read directly.

You give it your domain and it builds a ready-to-publish llms.txt file (a site summary plus the key pages) which you then host at /llms.txt on your site.

At the root of your domain, e.g. https://yourdomain.com/llms.txt, served as plain text. The llms.txt audit tool can then verify it is live and well-formed.

robots.txt tells crawlers what NOT to fetch. llms.txt tells AI crawlers what matters most and why. It is an invitation, not a restriction.