Key point. A valid llms.txt starts with one H1 line naming your site, then a one-line > summary, then ## sections that each list links as - Name: description. Paste your file below to check each rule and get a corrected copy.
llms.txt validator
Free tool · runs in your browser
llms.txt validator
Paste your llms.txt to check it against the format at llmstxt.org: the H1 name, the summary line, the sections and every link. You get a list of fixes and a corrected copy. Nothing is uploaded.
This checks the file's format only. It cannot tell you whether any AI system reads your llms.txt. Serve the file at https://yourdomain.com/llms.txt as plain text. No file yet? Build one with our llms.txt generator.
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What does the validator check?
It checks your file against the format published at llmstxt.org:
- the first line is a single H1 with your site or company name;
- a one-line blockquote summary follows the H1;
- sections use H2 headings, and no other heading levels;
- every section item is a Markdown link, with any description after a colon;
- links are full https:// addresses, with no duplicates;
- the file stays short (we flag files over 10 KB) and does not turn out to be HTML or a robots.txt file.
It also notices an Optional section, which the format reserves for links that can be skipped when space is short.
Does a valid llms.txt get me cited by AI?
We know of no published evidence that it does. The validator checks format only and cannot tell you whether any AI system reads your file. Treat llms.txt as low-cost hygiene: an accurate index of your most useful pages.
How do I fix the problems it finds?
Each finding comes with a fix. Mechanical ones (spacing, list markers, duplicates, relative links when you enter your site address, a missing summary marker) are applied in the corrected copy; check it before you upload. No file yet? Start with our llms.txt generator.
FAQ
Does the validator fetch my site?
No. It checks what you paste, in your browser. Nothing is uploaded.
Can I use relative links like /pricing?
Use full addresses. A reader that fetches llms.txt on its own may not resolve relative links. Enter your site address and the corrected copy will expand them.
Is a large llms.txt a problem?
The file is meant to be a short index. Keep your main pages in it, move the rest under ## Optional, and put full content in a separate llms-full.txt if you want one.
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