llms.txt explained: what it is, and whether you need one

llms.txt is a markdown file served at https://your-domain/llms.txt. It describes the site for language models: what you do, which pages matter, and how you want to be cited. The emerging shape is a title, a one-line summary, then linked sections.

It is optional. Most domains still do not ship one. That is why a clean explainer is useful now — adoption is early enough that a clear page can become the reference people bookmark.

llms.txt does not grant crawl access. It does not replace robots.txt. It does not guarantee ChatGPT, Claude, or Perplexity will mention you. Think of it as a machine-readable homepage for models that choose to read it, the same way a sitemap helps crawlers that choose to use it.

You need one if you want a single, stable URL that explains the product to AI systems and to humans who look for the file. You do not need one to pass an AI crawler check. amisearchable.cc treats llms.txt as informational: found or not found, never a badge fail.

If you already care about AI search visibility, adding a short llms.txt is cheap and easy to keep honest. Ours is at /llms.txt, with a longer version at /llms-full.txt.

# Example

> One sentence about the product.

This site allows AI search crawlers. See /robots.txt.

## Docs
- [Home](https://example.com/): what the product does
- [Pricing](https://example.com/pricing): plans

robots.txt answers “may this bot fetch the URL?” llms.txt answers “once a model is looking, what should it know?” Compare the two files.