What Is llms.txt? How to Write One and Whether It Works

llms.txt is a Markdown file placed at the root of a website that gives language models a short, curated map of the site: what it is, and which pages matter. The idea was proposed by Jeremy Howard on 3 September 2024 and is documented at llmstxt.org. It is a proposal. No standards body governs it, and nobody is required to read it.

Does it do anything? For Google, no: Google’s AI optimization guide says Google Search does not use llms.txt files and that making one will neither harm nor help your rankings. SE Ranking looked at 300,000 domains and found 10.13% had the file; its analysis concluded the file has no measurable effect on how AI systems see or cite your content. The honest case for writing one is small and cheap: assistants that read your site on request get a clean entry point, and you are forced to decide which ten to thirty pages describe your product.

We run one ourselves. askairank.com/llms.txt is 99 lines and 7,165 bytes with 71 Markdown links under eight H2 sections (checked 15.10.2026). When we reread it for this guide it still described four tracked engines and a free plan, a good example of why the file needs the same update habit as any other page.

Why it matters for AEO. llms.txt is a proposal, not a standard that search engines enforce. It costs an hour, it can help tools that fetch your site on request (for example an assistant reading your docs), and Google says it does not use the file in Search. Write it for that first group and expect nothing from the second.

1. Create a plain text file named `llms.txt` at the root of your site, so it opens at `https://yourdomain.com/llms.txt`.
2. Start with one H1 line: the name of your site or product. It is the only required part.
3. Add a blockquote with a two-sentence summary: what the product is and who it is for.
4. Add H2 sections (Product, Docs, Pricing, Comparisons) and under each a list of Markdown links, each with a short note after a colon.
5. Put secondary pages under an H2 called "Optional". Tools can skip that section when they need less text.
6. Keep it to the pages you would send a new colleague to. Link the live, canonical URLs only.
7. Check that the file returns 200 with a text content type, and update it whenever you add or remove a key page.

How to verify. Open `/llms.txt` in a browser and in curl. Confirm it returns 200, starts with `# Your Name`, and that every link opens without a redirect or 404.

# Acme Analytics

> Acme Analytics is a product analytics tool for B2B SaaS teams.
> It tracks activation and retention without cookies.

## Product
- [Pricing](https://acme.com/pricing): plans and limits
- [Integrations](https://acme.com/integrations): Segment, Stripe, HubSpot

## Docs
- [Quickstart](https://acme.com/docs/quickstart): install the snippet in 5 minutes

## Optional
- [Changelog](https://acme.com/changelog): release notes