llms.txt checker and generator

This llms.txt checker fetches /llms.txt and /llms-full.txt from a domain and tells you whether they follow the llmstxt.org format. It can also build a draft from the sitemap. The draft is a starting point: a person still has to write the descriptions.

No sign-up. Runs in your browser. Last reviewed November 4, 2026 by the Builderz team.

How it works

The format

An llms.txt file is Markdown. It starts with one H1 title, may have a blockquote summary and a few paragraphs, then H2 sections that each hold a list of links written as "- [title](url): optional note". A section named Optional marks links an assistant can skip when space is short.

What Check validates

Check fetches llms.txt and llms-full.txt over https and reports status, size, and whether the file was cut at the size limit. It parses the file and lists problems: a missing H1, no summary, empty sections, list items in the wrong form, and links that are relative or point to another host. It shows the first 200 lines of text files.

How Generate builds the draft

Generate reads sitemap.xml and, for a sitemap index, up to three child sitemaps. It keeps up to 200 same-host https URLs, groups them by first path segment, and writes one H2 per group. Pages with a single path segment go in a Pages group. The title is the host, the summary is a placeholder line you must edit, and no link has a description.

What it does not do

It does not crawl past the sitemap, run JavaScript, or follow redirects. It does not say whether any AI assistant reads the file, and the robots.txt panel only lists which crawler names appear. Nothing you enter is stored.

Questions about this tool

Do AI assistants read llms.txt?

This tool does not know. It checks that the file exists and follows the format. Whether a given assistant uses it is up to that assistant, and none of them is observed here.

Why are the descriptions left blank in the draft?

A sitemap lists URLs, not what each page is for. Writing a description from a URL alone would be a guess, so the draft leaves it to you.

Why does the check fail on a redirect?

The tool does not follow redirects, for the same reason it only fetches public https hosts. If example.com redirects to www.example.com, enter the www host.

What does the tool send to my site?

Plain GET requests for llms.txt, llms-full.txt, sitemap.xml, robots.txt, and up to three child sitemaps, with a user agent that names Builderz tools. Nothing you type besides the domain is sent.