Setting Up llms.txt in WordPress

Four ways to publish the file

There is no built-in llms.txt feature in WordPress core, so every method relies on either a real file on disk or a plugin that answers the request. Pick one. Running two at once is the single most common cause of confusing results.

At the time of writing, Yoast SEO, Rank Math and All in One SEO each include an llms.txt option, and several standalone plugins exist. Their settings move between releases, so follow the plugin's own documentation for where the switch lives. Whatever tool generates the file, read the result: generators tend to list recent posts with their excerpts as notes, which is a starting point rather than a finished file. The guide to thin llms.txt content explains what to improve.

A reminder about expectations: llms.txt is a proposal made by Jeremy Howard in 2024, and as far as we know no major AI provider has confirmed that its search or answer products use it. Setting it up in WordPress is quick and low risk, but it is not a substitute for crawlable, well structured pages.

How WordPress decides what to send for /llms.txt

Most WordPress problems with llms.txt come down to the order in which the web server and WordPress get to answer the request.

1. The web server checks for a real file first. The standard WordPress rules for Apache send a request to index.php only if no file or folder of that name exists, and typical nginx set-ups do the same with try_files $uri $uri/ /index.php?$args. So an llms.txt file sitting in the web root always wins.
2. If there is no file, WordPress loads. A plugin that has registered a rewrite rule for llms.txt, or that checks the request early, can then answer it.
3. If nothing claims the request, WordPress shows your theme's 404 page, with a 404 status and an HTML content type.

That order explains the most confusing symptom: you change the plugin settings and nothing happens. An old hand-uploaded file, or one a plugin wrote to disk months ago, is still in the web root and is being served instead. Check for it before anything else.

# From the WordPress root, over SSH
ls -la llms.txt llms-full.txt

# Or with WP-CLI, confirm permalinks are not set to Plain
wp option get permalink_structure

An empty result from the second command means Plain permalinks are in use. Rewrite-based methods cannot answer /llms.txt in that mode, because WordPress is not handling pretty URLs at all. Switch to any other structure under Settings, Permalinks, or use an uploaded file instead.

The custom mu-plugin method

If you want full control without another plugin, a must-use plugin can serve the file. Save this as wp-content/mu-plugins/serve-llms-txt.php (create the folder if it does not exist). It reads a Markdown file you maintain in wp-content/llms/, with one file per site so that it also works on multisite.

<?php
/**
 * Plugin Name: Serve llms.txt
 * Description: Answers /llms.txt with a Markdown file from wp-content/llms/.
 */

add_action( 'init', function () {
    add_rewrite_rule( '^llms\.txt$', 'index.php?serve_llms_txt=1', 'top' );
} );

add_filter( 'query_vars', function ( $vars ) {
    $vars[] = 'serve_llms_txt';
    return $vars;
} );

// Priority 0 runs before WordPress's canonical redirect (priority 10),
// so the URL is never rewritten to /llms.txt/ with a trailing slash.
add_action( 'template_redirect', function () {
    if ( ! get_query_var( 'serve_llms_txt' ) ) {
        return;
    }
    $file = WP_CONTENT_DIR . '/llms/llms-' . get_current_blog_id() . '.md';
    if ( ! is_readable( $file ) ) {
        status_header( 404 );
        header( 'Content-Type: text/plain; charset=utf-8' );
        echo "Not found\n";
        exit;
    }
    status_header( 200 );
    header( 'Content-Type: text/plain; charset=utf-8' );
    header( 'Cache-Control: public, max-age=3600' );
    readfile( $file );
    exit;
}, 0 );

After uploading it, flush the rewrite rules once, either by visiting Settings, Permalinks and pressing Save without changing anything, or with wp rewrite flush. Then put your file at wp-content/llms/llms-1.md for a single site; on multisite, each site uses its own blog ID in the file name. You can find the ID for each site under Network Admin, Sites.

The same pattern extends to llms-full.txt with a second rule and file. Keep generation, such as a script that rebuilds the Markdown on publish, separate from serving, so the serving code stays this small.

The fix, step by step

WordPress symptoms and their causes

Hosting and platform differences

Managed WordPress hosts

Most managed hosts give you SFTP or a file manager, so any of the four methods works. Some add their own server-level page caching that ignores WordPress cache plugins; if the file does not update, use the host's purge button or ask support to exclude /llms.txt from the server cache.

WordPress.com

On WordPress.com plans that do not allow plugins or file access, you cannot place a file at the root of the site. Plans that allow plugins can use a plugin-based method. Check your plan's features before spending time on it.

Subdirectory installs

If WordPress lives at example.co.uk/blog/ and the rest of the site is something else, the file belongs at the domain root, which WordPress does not control. Put it there by hand or through whatever runs the main site, and list the blog's key pages in it.

Headless WordPress

When WordPress only supplies content to a separate front end, such as a Next.js or Astro site, the front end owns the root of the domain. Generate the file there at build time from the WordPress REST API or GraphQL data. Treat it like any other static or framework site: the file is built alongside the pages, not served by WordPress.

Keeping a WordPress llms.txt current

WordPress sites change constantly, which is both the advantage of generating the file and the risk of writing it by hand.

• Plugin-generated files pick up new content, but also pick up content you would not choose, such as short announcements. Review the included post types and exclusions after adding new ones, for example when a new plugin registers a custom post type.
• Hand-written files need an owner. Add "update llms.txt" to your checklist for publishing key pages, renaming services and deleting pages.
• Theme and plugin changes can switch off or change the file without warning. Re-run the auditor after major updates, a change of SEO plugin or a move to a new host.
• Migrations between hosts or domains need the file checked on launch day, since search-and-replace tools may not touch a static file and plugin settings may not carry over.

For links that stop working and files that drift from the site, see broken links in llms.txt and a stale llms.txt.