Served correctly
The file answers at /llms.txt as plain text, not an HTML error page or a redirect loop.
llms.txt validator // free
Free llms.txt checker
Validate a live llms.txt file or pasted content: format, plain-text serving, broken links and weak descriptions. No login.
No score theatre
Observable checks only
Results are separated into broken output, judgement calls and checks that passed. We do not invent an AI visibility score from a file most platforms do not currently request.
Deterministic checks
What makes a usable llms.txt
Well formed
One H1 name, a short summary, H2 sections and Markdown links with useful descriptions.
Links that work
A bounded sample of linked URLs is requested to catch broken or redirected pages.
FAQ
Questions people ask
More free checks:
What does the llms.txt checker test?
Whether the root file is reachable as plain text, whether its heading, summary and sections follow the format, whether URLs are valid and not duplicated, whether descriptions add context, and whether a bounded set of links resolves.
Can I check a file before publishing it?
Yes. Paste the content instead of a URL. Pasted checks run entirely in your browser.
Do I need an llms.txt file?
It is optional. Google says you do not need AI text files to appear in its AI features. If you publish one, it should at least be valid.