Introducing the llms.txt Validator — Spec Checks, Paste or Fetch URL

Sites are adding llms.txt next to robots.txt and sitemaps so AI agents get a curated map of important pages — not a raw crawl of every marketing URL. The format is simple Markdown, but the details trip teams up: H1 must come first, list sections need proper - [name](url) items, relative links break offline, and oversized files stop being indexes at all.

The new llms.txt Validator makes those checks automatic.

What it does

• Paste mode — drop file contents; validation runs entirely in the browser.
• Fetch URL — enter a domain; we resolve /llms.txt, proxy the fetch (CORS-safe), then validate the body client-side.
• Spec-oriented rules based on the llmstxt.org community format: single H1, recommended blockquote summary, H2 file lists, Optional heading recognition.
• Line-level issues — errors, warnings, and info notes you can act on.
• Stats panel — sections, absolute vs relative links, size, Optional present.
• Load example — explore a valid sample before authoring your own.

What it intentionally does not do

llms.txt is not robots.txt. This tool does not generate crawl rules or block GPTBot — use the robots.txt Generator for that. It also does not invent ranking guarantees; it keeps your AI index structurally sound.

Who it is for

• Documentation and API product teams
• SEO / GEO specialists shipping AI-readable root files
• Agencies auditing client domains
• Anyone adding public/llms.txt before launch

Learn more

• llms.txt complete guide
• llms.txt vs robots.txt
• How to create llms.txt
• How to use the validator

Try the llms.txt Validator — free, no account required.