llms.txt Validator
Check your llms.txt file against the specification, from a URL or by pasting a draft before you publish it.
The most common failure is invisible in a browser
Open yourdomain.com/llms.txt in a browser and you will see something appear. That proves nothing. Many servers return the site homepage for any unknown address instead of a 404, so the file looks present while it does not exist.
The validator therefore checks what is actually served before anything else. It is the first thing a serious tool has to verify, and the one most online checkers skip.
Write the file, then validate it
If you do not have a file yet, our llms.txt generator produces one from your URL. This validator then checks the result, and checks it again after every rework of your site structure.
The classic mistake is creating the file once and forgetting it. An llms.txt pointing at deleted pages is worse than no file at all: it spends the model context window on dead links.
Why this matters for GEO
A malformed file is useless: A model that cannot read your index falls back to raw HTML, which is exactly what the file was meant to avoid.
Validation belongs before publishing: Paste mode removes the publish, notice, fix, redeploy loop.
Absolute links survive the journey: The file is read away from your site. A relative link has no origin left to resolve against.
Light beats exhaustive: Anything entering a context window displaces something else. A bloated index crowds out the useful content.
A valid llms.txt clears the path. Citeme then measures what counts: whether the engines cite you, and on which questions.
Frequently asked questions
Eight things, all drawn from the llmstxt.org specification. It looks for a single H1 giving the site name, a blockquote summarising what the site does, H2 sections grouping links by theme, and Markdown links with one-line descriptions after the colon. It then checks that links are absolute, that the file stays light, and that the server is returning plain text rather than an HTML page. The last check catches the most common failure by far. A server with no llms.txt often returns the site homepage instead of a 404, so the file looks present in a browser while containing nothing a model can use.