llms.txt validator
Check any site's llms.txt against the
llmstxt.org
spec — structure, link health, and the conventions that aren't actually in the spec.
Reads only /llms.txt at the location you give it. Nothing is stored.
Frequently Asked Questions
What is llms.txt?
A markdown file at /llms.txt that tells language models what a site is and where its important content lives, in a form they can read without parsing navigation, scripts and boilerplate out of your HTML. It was proposed by Jeremy Howard at llmstxt.org.
What does the spec actually require?
One thing: an H1 with the project or site name. The spec calls it the only required section. A blockquote summary, content sections and H2 file lists are all described as optional or 'zero or more'. This checker reports only the missing H1 as an error, and labels everything else by where the rule comes from.
Is llms-full.txt part of the spec?
No. It appears nowhere in the llmstxt.org spec. It is a widely used convention for a single file with the full content inlined, so a client does not have to follow every link. This checker reports it as a convention, never as a spec violation.
Does having an llms.txt improve my ranking?
There is no evidence that any search engine uses it as a ranking signal, and none of them have said they do. What it does is give a model reading your site a clean, current description you control, instead of one inferred from your markup. Treat it as content hygiene for answer engines, not as an SEO trick.
Do you store the sites I check?
No. The check runs per request and nothing about the target is written down. The file it reads is public by definition, and the checker only ever requests /llms.txt at the location you give it.
Want this done properly across your estate?
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