The llms.txt Guide: What It Is and How to Write One

llms.txt is a plain-markdown file served at your domain root (https://yoursite.com/llms.txt) that gives large language models a curated index of your most important pages — what your site is, and where the good stuff lives. Think of it as a sitemap written for readers instead of crawlers.

Why it exists

Crawlers see your site as thousands of URLs of equal weight, wrapped in navigation, cookie banners and boilerplate. llms.txt (proposed by Jeremy Howard in 2024, adopted steadily since) solves that by letting you say directly: here’s who we are, and here are the 20 pages that actually matter, each with a one-line description.

Does it actually help in 2026?

Honest answer: it’s an emerging standard, not a guarantee. Adoption among AI companies is uneven and none formally commits to it. But the cost is one text file, three of the checks in our visibility score reward controllable readiness rather than promises, and sites in developer-heavy and B2B niches increasingly report AI crawlers fetching the file. It’s the cheapest insurance in AEO — publish it and move on.

The format

Simple markdown with a defined shape:

# Your Business Name

> One-paragraph summary of what your business does, for whom,
> and what makes it distinctive.

## Products

- [Product A](https://yoursite.com/product-a): One line on what it is and who it's for
- [Product B](https://yoursite.com/product-b): One line on what it is and who it's for

## Guides

- [Big buyer guide](https://yoursite.com/guides/big-topic): What the reader will learn

## Company

- [About](https://yoursite.com/about): Who's behind it, founded when, based where
- [Contact](https://yoursite.com/contact): How to reach sales and support

Rules of thumb:

• H1 = your name, blockquote = your elevator pitch. These two lines get read most.
• Curate hard. 15–30 links beats 300. This is your highlight reel, not your sitemap.
• Describe every link in plain language with the words buyers actually use.
• Absolute URLs, and keep it current — a stale llms.txt pointing at dead pages is worse than none.

Some sites also publish llms-full.txt — full page content concatenated into one file — for docs-style sites. For most businesses the index format is the right one.

Serving it

Any static file host can serve it — it’s just text at /llms.txt with content type text/plain or text/markdown. Reference your sitemap in it if you like, and don’t block it in robots.txt (it happens more than you’d think).

Checklist

1. Write the file using the template above.
2. Upload to your domain root.
3. Verify https://yoursite.com/llms.txt returns it (not a 404 page with status 200 — our checker catches that trap).
4. Revisit quarterly.

Next: make sure the pages you just indexed are worth citing — the getting-cited playbook.