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Free llms.txt Validator

Paste your file to validate llms.txt against the spec in seconds. We test the title, summary, sections, and links, then score how ready your file is for ChatGPT, Claude, Perplexity, and other AI assistants.

Paste your llms.txt

Drop the file content

Open yoursite.com/llms.txt in your browser, copy everything, paste here.

Don't have one yet? Build it with our llms.txt Generator.

Paste your llms.txt on the left. We'll check it against the spec — title, summary, sectioned links, descriptions — score it, and flag what to fix for AI assistants.

What the checker tests against the llms.txt spec

A valid file isn't just well-formed Markdown — it's written so an AI under context pressure can use it. We check both.

Title + summary

Confirms a single H1 and a quotable `> summary` blockquote — the two elements AI assistants read first and quote most.

Sections + links

Parses every `## Section` and `- [name](url): description` link, flags malformed Markdown, and checks for absolute https:// URLs.

AEO score

Weighs each issue by how much it affects AI comprehension and gives you a 0–100 score plus a prioritized fix list you can copy.

Don't have an llms.txt yet? Build one with the free llms.txt Generator, then come back here to validate it. New to the spec? Read our AEO guides.

Frequently asked questions

Everything about validating llms.txt and what each check means for AEO.

What does the llms.txt validator check?
It parses your file against the llms.txt spec and checks the things that actually matter for AI assistants: (1) a single `# Title` H1, (2) a `> blockquote` summary right after it, (3) at least one `## Section` of links, (4) every link in valid `- [name](url): description` Markdown, (5) absolute https:// URLs, (6) a description on each link, and (7) an optional `## Optional` block. It scores the file out of 100 and lists exactly what to fix.
Is this the same as a generator?
No. A generator builds a new llms.txt from scratch. This validator checks one you already have — paste your existing file (or the live one at yoursite.com/llms.txt) and it tells you what's broken or missing. If you don't have a file yet, use our llms.txt Generator first, then validate the result here.
What is llms.txt?
llms.txt is a plain-text Markdown file at the root of your site (yoursite.com/llms.txt) that tells AI assistants what your site is about and which pages matter most. It was proposed in September 2024 by Jeremy Howard as a lightweight, LLM-friendly index — think 'sitemap.xml, but written for an AI'.
Why does the summary blockquote matter so much?
The `>` blockquote right after your H1 is the single most-quoted line in the file. When an AI assistant summarizes or recommends your site, it often lifts that sentence verbatim. A vague or missing summary means the AI writes its own — and may get you wrong. Our validator flags a missing or too-short summary as a high-priority fix.
Do link descriptions really change anything?
Yes. Each `- [Page](url): description` line gives an AI the context to decide whether a page is worth reading under a tight context window. Links without descriptions still work, but you're leaving the AI to guess from the URL. The validator scores description coverage and nudges you toward 100%.
Does a valid llms.txt guarantee AI citations?
No — it's necessary, not sufficient. A clean llms.txt raises the floor on how well AI assistants understand your site, but citations also depend on authority, schema, content depth, and presence on sources AI trusts (Wikipedia, Reddit, industry directories). Run a free AEO audit to see your full picture, not just the file.
Is the validator free? Does my file get uploaded?
Free, no signup, no limit. Everything runs in your browser — your llms.txt is parsed client-side and never sent to a server. Paste sensitive drafts safely.
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