llms.txt Validator & Link Checker
Free llms.txt validator: check H1, summary, H2 sections, markdown links, relative URLs, and HTTP status on up to 30 links. Paste or fetch.
- Enter a site URL or paste content
- Review the score and issue table
- Check linked URLs and export
- Browser-based — no install
- Instant results
llms.txt is a plain-text markdown file at your site root that tells automated readers what your project is called, what it does in one sentence, and which URLs matter most. The format is documented at llmstxt.org . It is not a replacement for robots.txt , sitemaps, or on-page SEO. Think of it as a curated reading list you are willing to stand behind. This guide explains how to write and fix the file. When you want a live score, broken-link list, and line numbers on a published or draft file, use the llms.txt Validator . That tool page focuses on reading validation output. This page focuses on authoring. What belongs in llms.txt Start with exactly one H1 line: # Your Site or Project Name . That title should match how you want the site named in an index, not a marketing slogan stuffed with keywords. Optional but recommended: a blockquote summary on the next lines: > One sentence about what the site offers. The summary gives parsers a quick context line before they hit link lists. If you skip it, some checkers warn even when the rest is valid. After the summary, add H2 sections. Each section is a group of related links. Common names are Docs , Blog , Products , or Tools . Under each H2, use markdown list lines: The note after the colon is optional. The link label should be human-readable. The URL should be the canonical https address you want cited, not a redirect hop unless you have no choice. Optional section and llms-full.txt Some sites add an H2 titled Optional for pages that are useful but not primary: privacy policy, changelog, older docs, or a status page. The name is a convention, not a hard rule in every consumer, but it signals lower priority…
Read the full guideWhat this validator checks
Enter a site URL and Scrawl fetches /llms.txt at the root (and reports whether /llms-full.txt exists). Or paste draft markdown and optionally give a site origin so relative links can be resolved and checked.
Validation follows the llmstxt.org shape: exactly one H1 title, an optional blockquote summary, H2 sections with markdown link lists (- [name](url): notes), and an Optional section when you want lower-priority links called out separately.
How to read the score and issue table
The score starts at 100 and drops for structural errors (missing H1, HTML instead of text, malformed list lines), warnings (relative URLs, empty sections, missing summary), and broken links from live HEAD/GET checks. Excellent and Good mean the file is publishable with minor cleanup. Needs work or Poor mean fix errors before you upload.
Each row in the issue table points to a line number when the parser knows it. Errors are blockers. Warnings are spec or hygiene issues that will not always break parsers but are worth fixing. Info rows cover optional files and check limits.
The link table lists up to 30 unique URLs from the file, with HTTP status and redirect hops. Only the first 30 unique addresses are checked per run.
Paste mode vs site URL
Site URL mode is for a live audit after you publish. Paste mode is for drafts from the llms.txt Generator or from your editor before upload. Add an optional origin URL in paste mode so /docs resolves to https://yoursite.com/docs during link checks.
What this tool does not do
It does not upload files, rewrite robots.txt, or prove that a specific AI product read your llms.txt. It validates markdown structure and checks that linked URLs respond. For broader AI crawl rules, use the AI Crawler Accessibility Checker.
Frequently Asked Questions
What is a valid llms.txt file?
A plain-text markdown file at your site root with one H1 (# site name), usually a blockquote summary (> one line), then H2 sections containing markdown links like - [Title](https://example.com/page): optional note. The llmstxt.org spec uses absolute https links in examples.
Does this checker fetch llms-full.txt?
When you enter a site URL, the tool notes whether /llms-full.txt exists at the root. It does not validate the full file body in this version. Structure validation focuses on /llms.txt or pasted content.
Why are relative URLs flagged?
Relative paths can work when the file is served from your domain, but the published spec and examples use absolute URLs. Relative links also make link checking ambiguous without a known site origin.
How many links are checked?
Up to 30 unique linked URLs per run, checked concurrently with limits. Duplicate URLs in the file count once toward that cap. HEAD is tried first; GET is used when HEAD is not supported.
How is this different from the llms.txt generator?
The generator builds a draft from your sitemap or manual sections. This validator scores an existing or pasted file, lists structural issues line by line, and checks whether linked pages respond.
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