llms.txt Validator - Validate and audit llms.txt files
The llms.txt Validator is a diagnostic developer utility designed to test and audit site configuration files against the official llmstxt.org v2 specification. It evaluates structural compliance, checks link integrity, and ensures that AI discovery files are properly configured and fully reachable by modern language models and automated agents. By analyzing files directly through a live URL or via direct content pasting, developers and SEO professionals can instantly identify syntax errors, delivery misconfigurations, and crawling obstructions.
Key Features
- Spec Compliance Audit: Parses markdown structure, H1 headings, blockquote placements, and subpath scopes against the llmstxt.org v2 specification.
- Full Link Health Check: Tests up to 100 links inside the file via HEAD and GET requests to identify broken URLs, timeouts, and redirect chains.
- Multi-UA Crawler Simulation: Simulates access requests across five user agents including GPTBot, ClaudeBot, and PerplexityBot to detect WAF blocks or content cloaking.
- Robots.txt Cross-Reference: Inspects domain access rules to highlight conflicting instructions that might unintentionally block AI agents from reading the target file.
- Delivery & Content-Type Validation: Verifies proper header declarations, flagging incorrect text/html configurations common on default platform setups.
- Lighthouse 13.3 Alignment: Predicts audit performance relative to Chrome Lighthouse Agentic Browsing standards for modern web applications.
This tool is ideal for web developers, documentation maintainers, and product builders optimizing technical visibility for AI coding assistants and search agents. Results include shareable diagnostic reports and JSON exports with copy-paste remediation patches for platforms like Nginx, Apache, and Cloudflare. The service is entirely free to use with no account or registration required.
