llms.txt Validator:
Is Your Site AI-Crawler Ready?
The llms.txt validator that checks every section of your file against the current spec - identifying missing required sections, formatting errors, broken links, and AI engine compatibility issues. Get a line-by-line validation report with fixes for every problem found.
The New Standard for Telling AI What Your Website Is About
llms.txt is a plain-text file placed at the root of your domain (e.g., example.com/llms.txt) that communicates your brand, key pages, and allowed content directly to AI language models and crawlers.
Proposed by Answer.AI in 2024, llms.txt is rapidly being adopted by AI crawlers including Perplexity, Claude.ai, and emerging AI search agents. Sites without a well-formed llms.txt give AI systems less context - which means fewer citations and less visibility in AI-generated answers.
Instant Validation in Three Steps
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Enter Your Domain
Type your domain (no need for the full path). Citerank automatically fetches your live llms.txt from the standard location.
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Spec & Readiness Analysis
The validator checks your file against the official llms.txt specification - title, description, sections, linked URLs, word count - and scores AI-readiness on 8 weighted signals.
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Get Your Grade and Fix List
Receive a letter grade (A+ to F), a score out of 100, and a ranked list of specific fixes with copy-paste examples - so you know exactly what to improve.
8 AI-Readiness Signals Scored
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Brand Title
The # heading must be present and contain your brand name. Missing titles cost 25 spec points - it is the most common critical error.
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Description Block
A > blockquote description below the title helps AI systems understand what you do and who you serve before crawling any pages.
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Structured Sections
Validates the presence of ## sections. Three or more well-named sections (About, Services, Resources) maximize AI parsing accuracy.
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Linked URLs
Counts internal URLs in sections. Five or more linked pages let AI crawlers follow your most important content for citation context.
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Content Depth
Checks total word count. Files under 50 words give AI too little context; 200+ words achieves a full readiness score on this signal.
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Artifact Detection
Catches common AI-generation artifacts - code fences, extra markdown - that break llms.txt parsers and reduce citation confidence.
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Section Diversity
Checks whether sections cover key categories: About/Overview, content/resources, and contact. Diverse sections improve AI context.
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HTTP Accessibility
Verifies that the file is publicly accessible at the standard URL path with a 200 OK status - a file that returns 404 is never read by AI crawlers.
Frequently Asked Questions About llms.txt
- What is a llms.txt validator?
- A llms.txt validator checks whether your llms.txt file is correctly formatted and spec-compliant - verifying that it has all required sections, uses the correct syntax, includes valid URLs, and follows the conventions that AI engines and language models expect. Without validation, a malformed llms.txt can be silently ignored by AI crawlers, wasting the effort of creating it. Citerank's validator checks your file against the current specification and identifies every issue.
- What should a valid llms.txt file contain?
- A valid llms.txt file contains: an H1 with your brand or site name, a brief description paragraph, at least one content section (H2 heading followed by a list of URLs with descriptions), and optionally an 'Optional' section for secondary content. The file must be in Markdown format, placed at the root of your domain (/llms.txt), and served with the correct content-type. Common validation failures: missing H1, incorrectly formatted URL lists, broken or relative URLs, and non-compliant section structures.
- How do I check if my llms.txt is working?
- To check if your llms.txt is working: (1) confirm it's accessible at yourdomain.com/llms.txt - any 404 means it's not deployed, (2) validate the file format with Citerank's validator to confirm spec compliance, (3) check your server logs for AI crawler user-agents (GPTBot, ClaudeBot, etc.) fetching the file - their visits confirm it's being read, (4) over 4-8 weeks, check whether your AI citation rate improves for the content you highlighted in llms.txt. Citerank's validator handles steps 1 and 2 automatically.
- Do AI search engines actually read llms.txt?
- Yes - major AI systems have confirmed they read llms.txt. Anthropic's Claude crawlers check llms.txt before processing site content. OpenAI's GPTBot respects llms.txt access declarations. Perplexity's crawler uses llms.txt for content discovery and brand context. Google has acknowledged llms.txt in its AI crawler documentation. The file doesn't guarantee citation, but it does give AI engines authoritative brand context and content priority signals they wouldn't otherwise have.
- What is the difference between llms.txt and robots.txt?
- robots.txt tells all web crawlers which pages to crawl or skip - it's access control for bots. llms.txt is content context for AI systems - it tells AI engines and language models who you are, what your most important content covers, and how you want your site to be represented. They serve different purposes and work together: robots.txt controls AI crawler access, while llms.txt provides the brand and content context that shapes how AI systems understand and describe your site. Both files should be maintained.
- Can I validate my llms.txt for free?
- Yes. Citerank's llms.txt validator is free to use with no account required. Enter your domain URL and get a full validation report in seconds - including section-by-section compliance checks, broken link detection, formatting error identification, and spec version alignment. The validator also checks your robots.txt for AI crawler access rules and flags any conflicts between your robots.txt settings and your llms.txt content declarations.