What is llms.txt, and does a WordPress site need one?

What is llms.txt?

llms.txt is a plain text file in Markdown that sits at the root of a site and points AI tools to the pages that matter. The question for a WordPress site is whether to add one, and what Yoast SEO’s new switch puts in it.

The idea comes from llmstxt.org, in a v2 page by Jeremy Howard, first published on 3 Sep 2024 and last changed on 10 Aug 2026. It describes itself as “a proposal to standardise on using an /llms.txt file to provide information to help agents use a website.”

The file holds a title, a short summary and lists of links. The proposal also suggests clean Markdown copies of your pages. It is a proposal, not a standard from a standards body.

Checking what a site’s llms.txt says, after the titles, schema and indexing that matter more, is part of our SEO and AI search fixes.

Does Google or ChatGPT read llms.txt?

Google says you do not need it. Its page “AI features and your website”, last updated 10 Dec 2025, says: “You don’t need to create new machine readable files, AI text files, or markup to appear in these features.”

For ChatGPT, Perplexity and the rest, we found nothing either way. None of the vendor pages we read on 18 Oct 2026 says their AI search reads llms.txt to choose what to cite. So we make no promise here, and you should be wary of anyone who does.

The proposal’s own page lists where the file is used today: coding agents, chat assistants that search, and the developer docs that OpenAI, Anthropic and Gemini publish with their own llms.txt. That is use by tools reading docs, not a ranking signal.

Does a WordPress site need llms.txt?

No. A WordPress site with clear pages that search engines can index has what Google’s AI features need. llms.txt is an extra, and a cheap one.

The basics come first. A file that points AI tools at your pages does nothing if every page says noindex. The usual culprit is one checkbox, covered in what the Discourage search engines box does.

If the basics are right and you want the file anyway, Yoast SEO can write it. Here is what it wrote for us.

How do you turn on llms.txt in Yoast SEO?

In Yoast SEO 28.7 the path reads Yoast SEO, Settings, General, Site features, then the AI tools group. The switch is labelled llms.txt and is off on a new install.

The text under it says: “Generate a file that points to your website’s most relevant content. Designed to help AI Assistants understand your website better.” There is a “Customize llms.txt file” button next to it. Turn the switch on and click Save changes.

What did Yoast’s llms.txt look like in our lab?

We ran WordPress 7.1.2 on PHP 8.4.26 with Yoast SEO 28.7 on 18 Oct 2026. The site had the default Hello world post and Sample Page. After we saved the switch, /llms.txt answered 200 with text/plain and 237 bytes:

# Lab Site

Generated by Yoast SEO v28.7, this is an llms.txt file, meant for consumption by LLMs.

## Categories
- [Uncategorized](http://127.0.0.1:9411/?cat=1)

## Optional
- [Sitemap index](http://127.0.0.1:9411/sitemap_index.xml)

It listed no page and no post, though the site had one of each. Yoast’s page selection was on “auto”, with no pages chosen.

A directory listing showed a real file, /var/www/html/llms.txt, 237 bytes, owned by www-data. Yoast writes the file once. It does not build it fresh on each request.

One small find: the file starts with a UTF-8 byte order mark, three invisible bytes before the #. Most readers skip them. In a PHP file the same three bytes cause the warning in our post on the WordPress headers already sent warning.

Why did our new pages not show up?

Because Yoast refreshes the file on a schedule, not when you publish. We published two pages, About us and Contact, and one post. The file stayed at 237 bytes with the same time stamp.

WP-CLI showed why. An event named wpseo_llms_txt_population runs once a week, and its next run was about a week out. On a live site, the file can lag new content by up to a week.

We ran the event by hand:

wp cron event run wpseo_llms_txt_population

The file was rewritten at 401 bytes. It now had a Pages section with About us and Contact, and a Posts section with the new post, above Categories and the sitemap. The default Hello world post and Sample Page were still not in it.

If you launch a service page, run that event, or check the file a week later. Setting up the file, or writing one by hand that names each service, is a one-problem fix at $45 on a WordPress site.

What happens when you switch it off?

Yoast deletes the file. After we saved the switch off, the web root had no llms.txt.

The address did not then return a clean 404. Our lab, on plain permalinks, answered /llms.txt with a 301 to /llms.txt/ and then the site’s normal HTML page. A site with pretty permalinks may answer differently. We did not test that.

Should you write llms.txt by hand instead?

You can, and you control every word. Ours is hand-written. Read at 12:16 PM ET on 18 Oct 2026, distrocode.com/llms.txt answered 200 as text/plain, 4,000 bytes. It names each service with one line, the four countries we work in, how to reach us and our reply time.

What Yoast does when a file already sits in the root, we did not test. Pick one method, and leave Yoast’s switch off if you keep your own file.

Want us to read your llms.txt with your titles, schema and indexing? Tell us about your site and we will say what to fix first.

Not sure what is wrong yet? Ask for the free site check: send the site address and we reply in writing within 2 business days.