Validador de llms.txt

How to use

1. Paste your llms.txt content into the text field, or click Upload file to load it from disk.
2. Click Validate — the tool checks structure, H1 presence, section formatting, and Markdown link syntax, and lists every issue with its line number.
3. Fix any errors (red) and warnings (amber) in your text editor, paste the updated content, and re-validate until you see the green Valid llms.txt badge.

Related use cases

• llms.txt format checker
• Validate llms.txt file online
• llms.txt syntax check
• llmstxt spec compliance checker
• AI crawler file validator

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Preguntas frecuentes

Does my llms.txt content get uploaded anywhere?

No. All validation runs entirely in your browser using JavaScript. Your file content never leaves your device — no server, no upload, no account required.

What is llms.txt and why do I need to validate it?

llms.txt is a Markdown-based file placed at the root of a website that tells AI language models and crawlers what content is available and how to access it — similar to robots.txt but designed for LLMs. Validation ensures your file follows the specification: a required H1 title, optional blockquote description, H2 sections with properly formatted Markdown links, and an optional "## Optional" section for lower-priority content.

What errors does this validator check for?

The validator checks: missing or misplaced H1 heading, invalid Markdown link syntax in list items (links must be [text](url) format), malformed URLs, duplicate H1 headings, empty sections with no links, bare text lines inside sections, lines that do not fit the spec structure, and mixed content in the Optional section.

What file size can I validate?

The validator handles any reasonable llms.txt file in the browser — there is no server-side size limit. Typical llms.txt files are a few kilobytes. Even large files with hundreds of links validate instantly.

Which browsers are supported?

Any modern browser with JavaScript enabled: Chrome, Firefox, Safari, and Edge. No WebAssembly or WebGPU is used — just standard JavaScript DOM APIs, so even older mobile browsers work.

Can I validate an llms-full.txt file too?

Yes. The validator applies the same rules to llms-full.txt and any other llms.txt-family file. The spec allows an llms-full.txt at the root to provide expanded context for AI models that can handle longer documents.