What is llms.txt, and is it worth writing?
llms.txt is a short Markdown file at the root of your site that tells language models what the site is, what it costs and which pages matter. Google Search ignores it, and in a June 2026 Ahrefs study 97% of llms.txt files received no requests at all, so it won’t lift your rankings. It’s cheap to write, and only useful if it says exactly what your pages say.
What llms.txt is
llms.txt is a plain Markdown file, served at /llms.txt, that summarises a website for language models and AI agents: what the site is, who runs it, and which pages to read. Jeremy Howard proposed it on 3 September 2024, and the proposal was last updated on 10 August 2026 (llmstxt.org). Think of it as a short briefing note for a machine that has only a few seconds to understand you.
What it is not
- Not robots.txt. It doesn’t allow or block any crawler. Access is decided by robots.txt and by your CDN or firewall (see Cloudflare is blocking AI crawlers).
- Not a sitemap. Search engines find your pages through links and sitemap.xml, not through llms.txt.
- Not a ranking signal. Google says so explicitly, and there is no public evidence that any assistant ranks sites by it.
- Not a place for claims your pages don’t make. If a fact isn’t visible on your site, it doesn’t belong in llms.txt either.
Does anyone read it?
Less than the hype suggests. Here is what the evidence says, strongest first.
| Source | What it found | Type |
|---|---|---|
| Google Search Central, AI optimization guide (updated 10 July 2026) | Google Search doesn’t use llms.txt or other “AI text files”; creating one neither helps nor harms rankings | Official documentation |
| Ahrefs, 137,000 sites (15 June 2026) | 28% of domains publish llms.txt; 97% of those files received zero requests | Third-party study |
| Our sample site, 21–28 September 2026 | ChatGPT repeated a sentence that appeared in the first paragraph, the meta description and llms.txt; we can’t tell which copy it read | Own measurement |
Google Search ignores it
Google’s AI optimization guide lists llms.txt among the things you can skip for Google Search, including its AI Overviews and AI Mode. Google’s changelog entry of 15 June 2026 adds that it’s fine to keep such files for other services that use them.
Most files are never requested
In Ahrefs’ study, 97% of llms.txt files got no requests at all in the period measured, and most of the requests that did arrive came from bots that aren’t AI assistants (Ahrefs, 15 June 2026; third-party study).
What we saw on our own sites
Our sample site’s llms.txt once listed a different price from one of its feature pages. Nothing broke in search, but an assistant reading both would have had two answers to “how much does it cost?”. We fixed it by generating the pages and llms.txt from one facts file (own measurement, September 2026).
The format
The only required part is an H1 with the site’s name. After it come a blockquote summary, optional plain paragraphs, and H2 sections that list links, each with a short note. A section called “Optional” holds links an agent can skip (llmstxt.org). This is the skeleton from appendix B of our book:
# [Brand] [category word]
> [Brand] is a [product type] that turns [input] into [output]. [The main difference, in one sentence].
> Operated by [company name] ([country]).
Key facts: [pricing model, lowest price, trial], [cancellation], [usage limits].
Not to be confused with: [Brand] is not [similarly named product]; it is not a [big company] product.
Limits of the evidence: [the test behind your main claim and its size, stated plainly].
## Product
- [Home](https://yoursite.com/): what it is
- [Pricing](https://yoursite.com/pricing): plans and prices
- [Situation page](https://yoursite.com/...): [the four-part sentence for that situation]
## Guides
## Comparisons
## Optional
- [Terms](https://yoursite.com/terms), [Privacy](https://yoursite.com/privacy)
Rules for the content
- The blockquote is your one sentence, word for word the same as your home page’s first paragraph and meta description.
- Add the not-X line if your name can be confused with anything else.
- Every price and claim matches your pages exactly; generate both from the same data.
- List your 10–20 most important pages, one line each.
- State the limits of your evidence plainly, as you would on the page.
llms-full.txt
Some sites also publish /llms-full.txt with longer text: prices, FAQ answers, the opening of each guide. It’s optional. If you have one, put the long material there and keep llms.txt short.
The one-sentence rule
The useful part of llms.txt isn’t the file; it’s the discipline of writing one sentence that says what you are, in four parts: what the customer brings, what you do, what they get, and which fear is unnecessary. Put that same sentence in three places: the first paragraph of your most important page, that page’s meta description, and llms.txt. On our sample site, ChatGPT repeated all four parts of it in two sessions on 28 September 2026 (own measurement). More on the sentence in the Katman method.
Keep it short
Our sample site’s llms.txt grew to 65 KB, bigger than its llms-full.txt, because it listed every page family. That defeats the purpose of a summary, and it’s on our list to slim down to the main product and one link per language (own measurement, 29 September 2026). A good llms.txt fits on one screen.
Common mistakes
- Writing llms.txt before fixing rendering: if your pages are empty without JavaScript, llms.txt can’t make up for it (see six traps for vibe-coded sites).
- Hand-editing it separately from the site, so prices and claims drift apart.
- Pasting in every URL of the sitemap.
- Marketing language in the summary: “the leading platform for…” gives an assistant nothing to repeat.
- Selling it as a service. It’s a small file, and the evidence says it’s hygiene, not a growth lever.
How Katman generates it
katman_generate builds llms.txt from your research file (.katman/research.json): your name and category as the H1, the four-part sentence as the blockquote, the not-X line, your prices as written on your pricing page, and your key pages with one line each. It returns the content and the target path, writes the file only when called with write: true, and never replaces an existing file unless you also pass overwrite: true. katman_lint_content then checks that your home page, your meta description and llms.txt use the same sentence, and flags any price that differs. The details are in the tool reference.
Should you bother?
Yes, if it takes you ten minutes and you keep it in sync with your pages. No, if it’s taking time away from the things with stronger evidence: letting AI search bots in, putting your text in the HTML, and writing pages for the situations your customers describe. Treat llms.txt as a tidy summary, not a strategy.
Written by the Katman team, Rnify Limited. Google, llmstxt.org and Ahrefs pages checked 30 September 2026.
Frequently asked questions
Does Google use llms.txt?
No. Google says Google Search ignores llms.txt, so creating one neither helps nor harms your visibility or rankings (AI optimization guide, updated 10 July 2026).
Do ChatGPT or Claude read llms.txt?
Rarely. In Ahrefs’ June 2026 study of 137,000 sites, 97% of llms.txt files received zero requests; assistants mostly read your normal pages through their search crawlers.
Where does llms.txt go?
At the root of your domain, as https://yoursite.com/llms.txt, served as plain text or Markdown. A file covers the URLs under its path.
What’s the difference between llms.txt and llms-full.txt?
llms.txt is a short index with one line per key page; llms-full.txt carries fuller text such as prices, FAQ answers and guide openings. Keep llms.txt the smaller of the two.
Should llms.txt include my prices?
Yes, if your pricing page shows them, in exactly the same words and numbers. A price that differs from your pages is worse than no price at all.
Can llms.txt hurt my site?
Not in Google Search, which ignores it. It can hurt your credibility if an assistant reads it and it contradicts your pages.
Should I pay someone to write my llms.txt?
No. It takes minutes to write from your one-sentence description and your page list, and the evidence that it changes AI visibility is weak.