Free llms.txt Checker
Is your llms.txt valid?
We fetch /llms.txt and /llms-full.txt, check they are real text files rather than an HTML error page, and validate the structure against the llmstxt.org format — then show the rest of your AI visibility report.
- files checked
- 2files checked
- format rules
- 5format rules
- AI visibility report included
- FullAI visibility report included
- no sign-up
- $0no sign-up
The format
What a valid llms.txt looks like
One H1 with your name. A one-line blockquote saying what you do. Optional context. Then H2 sections, each a list of links to your most important pages with a short note after each.
Keep it honest and short. It is a map for a model, not a second homepage — and on its own it will not fix a crawler block or a JavaScript rendering problem, which the full report checks for.
# Acme Plumbing > Acme Plumbing is a licensed residential and commercial plumber serving Austin, Texas since 2009. Emergency call-outs 24/7. Fixed-price quotes before any work starts. ## Services - [Emergency plumbing](https://acme.example/emergency): 24/7 call-out, 60-minute response in Austin - [Water heaters](https://acme.example/water-heaters): repair and replacement, gas and electric ## Company - [About](https://acme.example/about): licences, insurance, team - [Pricing](https://acme.example/pricing): call-out fee and hourly rates
Questions
Questions about llms.txt
Straight answers, including the ones where the honest answer is “nobody can measure that”.
What is the llms.txt format?
A markdown file served at /llms.txt. It starts with one H1 heading naming the site, followed by a blockquote with a one-line summary, optional paragraphs of context, and H2 sections that each contain a list of links in the form - [Page name](https://…): short note. An optional /llms-full.txt can hold the full text of your key pages.
Does ChatGPT or Google use llms.txt?
Not that they have confirmed. As of September 2026 no major AI engine has said it reads llms.txt when answering. It costs little to publish and some developer tools and agents do read it, but it will not fix a crawler block or a JavaScript rendering problem, which matter far more.
What does the llms.txt checker validate?
That the file exists and is served as text rather than an HTML error page, that it starts with exactly one H1, whether it has a blockquote summary, whether its H2 sections contain markdown link lists, and whether those links are absolute URLs. It also checks for /llms-full.txt.
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