Does llms.txt actually work? What the evidence says

As of October 2026, there is no public evidence that llms.txt makes ChatGPT, Claude, Perplexity or Google cite your site more often. Google says its Search ignores the file, no major AI search engine documents reading it, and log studies find AI crawlers rarely request it. It is still a useful, cheap convention for developer docs that people feed to coding assistants, so the honest answer is: publish one if it costs you little, but do not expect it to move AI visibility.

What is llms.txt?

llms.txt is a Markdown file at the root of a site, at /llms.txt, that gives language models a short, curated map of the site. The proposal at llmstxt.org was published by Jeremy Howard of Answer.AI on September 3, 2024. Its reasoning is practical: context windows are too small to read a whole website, and converting HTML full of navigation, ads and scripts into clean text is error-prone. A hand-written index solves both.

The format is simple. Only the first line is required:

# Acme Plumbing

> Licensed plumbers in Austin, Texas. Emergency repairs, water heaters and
> drain cleaning, 7 days a week.

## Services

- [Water heater repair](https://acme.example/water-heaters): Tank and tankless, same-day
- [Drain cleaning](https://acme.example/drains): Kitchen, bathroom and main lines

## Optional

- [About us](https://acme.example/about): Licensing, insurance and service area

An H1 with the site name, a blockquote summary, optional notes, and H2 sections with lists of links. A section named Optional marks links an agent can skip when it needs less context. The proposal also suggests offering a clean Markdown copy of important pages at the same address plus .md. Some documentation platforms add a second file, llms-full.txt, with the full text of every page; that is a common convention rather than part of the core proposal.

Does Google use llms.txt?

No, and Google has said so in its own documentation. The Search Central guide to optimizing for generative AI features (last updated July 10, 2026) says: “You don't need to create new machine readable files, AI text files, markup, or Markdown to appear in Google Search,” and that Google Search ignores these files. Google's separate page on AI features and your website adds that “there are no additional requirements to appear in AI Overviews or AI Mode, nor other special optimizations necessary.”

Google's search staff had said the same thing informally for over a year. In April 2025, John Mueller wrote on Reddit's r/TechSEO that “none of the AI services have said they're using LLMs.TXT” and compared the file to the keywords meta tag, as reported by Search Engine Journal. The comparison is pointed: the keywords meta tag was what site owners claimed their pages were about, and search engines stopped trusting it for exactly that reason.

There is one wrinkle. Chrome's Lighthouse added an llms.txt audit in its agentic browsing category. It treats a missing file as not applicable and only flags a server error when fetching it. That audit is about browser agents, not Search rankings, and Search Engine Journal covered the mixed messages between the two Google teams.

Do ChatGPT, Claude and Perplexity read llms.txt?

None of them says it does. OpenAI's crawler documentation describes GPTBot, OAI-SearchBot and ChatGPT-User and how to control them in robots.txt; it does not mention llms.txt. Anthropic's crawler article covers ClaudeBot, Claude-SearchBot and Claude-User the same way. That does not prove they never read it, but it means nobody has committed to it, and there is no documented way it feeds rankings or citations.

The best evidence is what crawlers actually request. Server-log studies so far point the same way:

Smaller single-site write-ups report the same pattern: robots.txt fetched hundreds of times by AI crawlers, llms.txt rarely or never. Treat any one study with care, since the samples are small and bots change, but there is no published log study showing AI search crawlers using llms.txt as a routine input.

So who actually uses llms.txt?

Developers, mostly. Large documentation sites publish one, including Anthropic's Claude docs, Stripe's docs, Cloudflare's developer docs and Vercel. The use case is concrete: a developer pastes the URL into a coding assistant, or an agent tool fetches it, and gets a clean index of the docs instead of crawling HTML. That is retrieval on request, which is what the proposal was designed for, and it is a different thing from an AI search engine deciding which businesses to recommend.

Should you add llms.txt to your site?

If you do publish one, do it in a way that cannot backfire:

1. Generate it from your real pages, most important first, so it never claims anything your site does not say.
2. Keep it to a title, a one-paragraph summary and the 20 to 150 links that matter. Put secondary pages under an Optional heading.
3. Serve it as plain text with a 200 status at /llms.txt. A server error is the one thing Lighthouse's audit flags.
4. Regenerate it when you add or remove important pages, and check the links still resolve.
5. Do not build separate, different content for bots. Search engines treat content shown only to crawlers as cloaking risk, and Google's guide says it is not needed.

Our free llms.txt generator builds a file from your pages in the format above, and the llms.txt checker validates an existing one. Inside SEO Rank Fixer, the AI visibility panel shows whether a site publishes llms.txt and offers a starter file built from the pages we have read, most-searched first.

What works better than llms.txt for AI visibility?

The things that demonstrably affect whether AI answers can find and quote you are less novel:

1. Let the right crawlers in. A robots.txt or CDN rule that blocks OAI-SearchBot or Claude-SearchBot removes you from those answers. Check with the AI crawler checker, and if you use Cloudflare, read whether it is blocking ChatGPT and Claude.
2. Get indexed by Google and Bing. AI answers lean on search indexes. See how to get indexed fast.
3. Answer the question on the page. Clear, specific answers near the top of a page are easier to quote. Our AEO guide covers how.
4. Be mentioned elsewhere. Reviews, directories and articles that name you shape which brands assistants recommend. The guide to getting recommended by ChatGPT goes through it.

If you want to see where you stand rather than guess, SEO Rank Fixer's AI visibility check (on Pro) asks ChatGPT and Claude your customers' questions with live web search and shows whether they name or cite you, and who they cite instead. For more terms used here, see the glossary.