Free tool

llms.txt checker

Enter a website. We read its /llms.txt against the format at llmstxt.org, open its first links, look for llms-full.txt, and when there is no usable file, draft one from the front page for you to edit. Nothing is stored.

Check a websitehttps://Free, no sign-up, ten checks an hour.

What the check looks at

  • The file itself: that /llms.txt answers with text, not with a web page, which is what many sites send for an address they do not have.
  • The format: one H1 title first, a blockquote summary after it, text without headings, then H2 sections whose list items are links, [name](url): notes.
  • The links: the first 20 are opened, and any that do not open are listed.
  • llms-full.txt: whether the site publishes one beside it.

Questions

What is llms.txt?

A plain-text file in Markdown at a site’s root, /llms.txt, proposed at llmstxt.org as a short guide for language models: the site’s name, a one-paragraph summary, and lists of links to the pages worth reading, each with a note on what it holds.

Do ChatGPT, Claude or Perplexity use llms.txt?

There is no published evidence that the assistants use llms.txt to choose what they recommend. It is cheap to add and can help tools and agents that do read it; treat it as a small signal at most.

What is the difference between llms.txt and robots.txt?

robots.txt tells crawlers what they may fetch. llms.txt allows and forbids nothing; it only points at what to read. A crawler shut out in robots.txt is not let in by llms.txt.

What does the Optional section mean?

In the format, a section called Optional holds secondary links that a model can skip when it needs a shorter context.

What is llms-full.txt?

It is not part of the format at llmstxt.org. Some documentation tools publish one: the whole documentation in a single file. The check shows whether a site has one.

Where does the file go?

At the root of the site, https://yoursite.com/llms.txt. The format also allows a file under a path, such as /docs/llms.txt, which covers the pages under that path.

Whether the AI crawlers may read the site at all is a separate question: the AI crawler check reads robots.txt and the firewall for 13 of them. To see what the assistants say about you, try the free visibility check.