What Is llms.txt? What It Does, Who Reads It, and How to Add One

Quick answer: llms.txt is a plain-text Markdown file at the root of a website (yourdomain.com/llms.txt) that gives AI tools a short summary of the site and a list of its most useful pages. It was proposed by Jeremy Howard of Answer.AI in September 2024 and is not an official standard. It’s optional: Google says you don’t need special AI files to appear in its AI features, and in June 2025 Google’s John Mueller said no AI system was using it yet. Adding one takes minutes (Yoast, Rank Math and All in One SEO can generate it), but don’t expect it to change your rankings on its own.

What llms.txt is

Large language models read websites the hard way: they fetch HTML full of navigation, scripts and cookie banners, and have to work out what matters. The llms.txt proposal, published on llmstxt.org, suggests a shortcut: one small Markdown file that says what the site is about and points to the pages worth reading.

Think of it as a hand-written table of contents for machines. It sits next to robots.txt and your XML sitemap, but it does a different job from both (see the comparison below).

What goes in an llms.txt file

The format is plain Markdown, in this order:

1. An H1 with the site or project name. This is the only required part.
2. A short summary in a blockquote (a line starting with >) with the key facts a reader needs.
3. Optional detail in normal paragraphs or lists: what the site covers, how its content is organised.
4. Sections of links, each under an H2, written as - [Page name](URL): short note.
5. An “Optional” section for secondary links that a tool can skip when it needs a shorter context.

The current version of the proposal also suggests offering clean Markdown copies of important pages (for example page.md) and pointing to them from the HTML. That part is useful mainly for documentation sites; most WordPress sites can skip it.

A real example: our own llms.txt

Here’s the file we serve at imageseo.io/llms.txt. Note what it leaves out: no marketing claims, no list of every blog post, no statistics we can’t back up.

# ImageSEO

> ImageSEO is a WordPress plugin that uses AI to write image alt text, titles, captions and descriptive file names, when images are uploaded or for a whole media library at once. Free for 10 images a month; paid plans start at €4.99 a month.

ImageSEO runs on WordPress only, including WooCommerce product images and NextGEN Gallery. It does not compress or convert images, so it is used alongside compression plugins. ...

## Product
- [ImageSEO](https://imageseo.io/): what the plugin does and how it works
- [Pricing](https://imageseo.io/pricing/): plans, monthly image limits and the 14-day money-back guarantee
- ...

## Guides and data
- [Image SEO guide](https://imageseo.io/images-seo-optimization/): alt text, file names, formats, lazy loading, sitemaps
- [Alt text study](https://imageseo.io/alt-text-study/): 306,634 images on the 10,000 most-visited homepages
- ...

## Optional
- [Blog](https://imageseo.io/blog/)

Does llms.txt help SEO or AI visibility?

Honestly: there’s no evidence that it does yet. Here’s what the primary sources say.

• Google doesn’t require it. Google’s documentation on AI features says you don’t need new machine-readable files, AI text files or special markup to appear in AI Overviews or AI Mode. A page needs to be indexed and eligible to show with a snippet, nothing more.
• Google says AI tools weren’t reading it. On 17 June 2025, John Mueller wrote on Bluesky that “no AI system currently uses llms.txt”. He pointed to server logs: chatbots fetch normal pages, but not that file. He added that this could change.
• Chrome’s Lighthouse now checks for it, lightly. Lighthouse has an llms.txt audit in its agentic browsing section. It only flags a server error when fetching the file; a missing file (404) counts as not applicable, because the file is optional.

So treat llms.txt as cheap insurance, not a ranking lever. If you want to know whether anything reads yours, check your server’s access logs for requests to /llms.txt and see which user agents make them.

llms.txt vs robots.txt vs XML sitemap

A common mix-up: llms.txt does not control access. If you want to keep AI crawlers out, that’s a job for robots.txt.

How to add llms.txt in WordPress

With Yoast SEO

Go to Yoast SEO → Settings → Site features, find llms.txt under AI tools and switch it on. Yoast builds the file automatically, refreshes it weekly and gives priority to your cornerstone content; you can also pick the pages by hand. According to Yoast, the feature isn’t available on multisite.

With Rank Math

Rank Math has an llms.txt module. Once it’s on, its settings let you choose which post types and taxonomies to include, cap the number of entries, and add your own text or links. The file is served at /llms.txt.

With All in One SEO

AIOSEO’s documentation says its llms.txt generator is enabled by default and can be switched off. Its settings sit with the sitemaps. AIOSEO also offers a longer llms-full.txt with the full text of your posts in its Pro version.

By hand

Write the file in any text editor, save it as llms.txt and upload it to the root folder of your site (the one with wp-config.php). Then open yourdomain.com/llms.txt and check two things: that it shows as plain text, and that the address doesn’t redirect. We found the second problem on our own site. WordPress was redirecting /llms.txt to a page with a similar slug, so every tool asking for our file got an HTML page instead. A static file in the root fixed it.

Use only one method. Two plugins generating the file, or a plugin plus a hand-made file, will conflict.

How to write a good llms.txt

• Lead with facts. What the site or product is, who it’s for, what it costs, what it doesn’t do. A tool quoting your file should get the facts right.
• Link 10 to 30 pages, not 3,000. Your most useful guides, product pages and documentation. The sitemap already lists everything.
• Write a note after each link so a reader knows what’s on the page before opening it.
• Don’t add “cite us” statistics. If a number isn’t on your site with a source, it doesn’t belong in a file that AI tools might repeat word for word.
• Keep it current. Update it when prices, product names or key pages change.

What llms.txt can’t do for your images

An llms.txt file describes pages, not pictures. When Google, AI Overviews or a chatbot needs to understand what an image shows, it relies on the alt text, the file name and the text around it on the page. In our crawl of the 10,000 most-visited homepages, 11.3% of 306,634 images had no alt attribute at all. That gap matters more than any summary file. You can describe a single image for free with our alt text generator, or let the ImageSEO plugin handle a whole WordPress media library.

Frequently Asked Questions

Is llms.txt mandatory?

No. It’s a proposal, not a standard, and Google says no special AI file is needed to appear in its AI features. A missing llms.txt doesn’t hurt you.

Does Google use llms.txt?

Google hasn’t said it uses llms.txt for Search or AI Overviews, and its documentation says you don’t need it. Lighthouse checks the file only for server errors.

Do ChatGPT, Claude or Perplexity read llms.txt?

None of them has confirmed using it for answers. In June 2025 Google’s John Mueller said server logs showed AI systems fetching pages but not llms.txt. The reliable way to know for your own site is to check your access logs.

Where does the llms.txt file go?

At the root of your domain, so it opens at yourdomain.com/llms.txt. The proposal also allows a file in a subfolder that covers only that part of the site.

Can llms.txt block AI crawlers?

No. It only offers information. To block or allow specific crawlers, use rules in robots.txt.

What is llms-full.txt?

A longer companion file containing the full text of your content rather than links to it. Some tools, such as AIOSEO Pro, generate one. Like llms.txt, it’s optional.