Validate Your llms.txt File
Check your llms.txt against the official spec. We validate structure, sections, links, and content quality — then give you a grade with specific fixes.
We'll fetch yoursite.com/llms.txt and validate it
Why this matters
AI crawlers prioritize structured signals
ChatGPT, Claude, and Perplexity crawlers look for llms.txt before parsing your HTML. A valid llms.txt means AI describes your product accurately and cites you in answers — invalid format means you're skipped.
Most llms.txt files have errors
We've validated 1,000+ llms.txt files. 60% are missing required sections, 30% return HTML soft-404s, 20% are too short. Even a valid-looking file often fails the spec on details that matter for AI parsing.
Get a grade and exact fixes
Our validator scores 10 specific checks against the official spec — H1 present, sections detected, link count, length, plain text only — and returns a letter grade with copy-paste fixes for every issue found.
How it works
Enter your website URL or paste your llms.txt content
We validate against 10 spec checks: H1, tagline, sections, links, length, format, key topics
Get a grade (A-F) with score 0-100 and specific fixes for every failed check
Frequently Asked Questions
What is the llms.txt specification?
The llms.txt specification (proposed by Jeremy Howard at Answer.AI) defines a Markdown file at /llms.txt that tells AI crawlers what your product does. It uses a single H1 for the product name, a blockquote tagline, then H2 sections like 'What We Do', 'Key Features', 'Pricing', 'Use Cases', plus Markdown links to your most important pages. Our validator checks against this spec and identifies missing sections or format errors.
How do I validate my llms.txt file?
Two ways: (1) Enter your website URL above and we'll fetch yoursite.com/llms.txt and validate it against the spec. (2) Paste your llms.txt content directly. Either way, you get a 0-100 score, grade (A-F), and a list of specific fixes for any issues.
What does a good llms.txt look like?
A good llms.txt has: a single H1 with your product name, a blockquote tagline (1-2 sentences), 3-7 H2 sections covering 'What We Do' / features / pricing / use cases / target users / integrations, 3-10 Markdown links to your most important pages, total length 800-3000 characters, and pure Markdown (no HTML). It mentions your brand name multiple times and uses plain factual language AI can quote directly.
Why isn't my llms.txt working?
Common issues: (1) Wrong location — must be at yoursite.com/llms.txt, not /llms-txt or /docs/llms.txt. (2) Wrong content type — server returning HTML instead of plain text (a soft 404). (3) Empty or too short — under 200 characters means AI can't extract anything. (4) HTML tags inside — should be Markdown only. (5) No H1 or sections — AI can't parse unstructured text. Our validator checks all of these.
What's the difference between llms.txt and llms-full.txt?
llms.txt is a concise summary (800-3000 chars) — the elevator pitch for AI crawlers. llms-full.txt is an expanded version with more detail, often including full documentation pages. Most sites only need llms.txt; technical products with extensive docs may add llms-full.txt as a complement. Our validator focuses on llms.txt; treat llms-full.txt as a longer-form version of the same structure.
Do AI crawlers actually read llms.txt?
Yes — increasingly. ChatGPT, Claude, Perplexity, and Anthropic's crawlers prioritize llms.txt as a structured signal because it's faster than parsing HTML and gives them authoritative product info from you. Google's Gemini also uses similar structured signals. The trend is clear: sites with valid llms.txt get cited more often in AI answers than sites without.
How long should my llms.txt be?
800-3000 characters is the sweet spot. Under 800 chars usually means missing key info. Over 5000 chars risks being truncated by AI parsers. Aim for clear, factual content that covers your product name, what it does, key features, pricing, use cases, and links to important pages — without filler.
Where should I host my llms.txt file?
At your site root: yoursite.com/llms.txt. In Next.js, place it in /public/llms.txt. In WordPress, upload to your site root directory. In Hugo or other static site generators, place it in the static folder. The file must be accessible without authentication and return content type text/plain or text/markdown.
Related Free Tools
llms.txt Generator
Create a valid llms.txt in 30 seconds
llms.txt Specification
Full technical reference and examples
AI Crawler Checker
Check if AI bots can access your site
AI Visibility Audit
Full 25+ signal AI visibility scan
FAQ Schema Generator
#1 most-cited data type by AI
Robots.txt Analyzer
Check if you block AI crawlers
Want the complete picture?
Run a full AI visibility audit — 25+ signals, fix roadmap, and AI-generated files.