Question 1

What is llms.txt?

Accepted Answer

llms.txt is a plain-text file at the root of your domain — analogous to robots.txt or sitemap.xml — that tells large language models what your site is about, what you sell, and which pages matter. It was proposed by Jeremy Howard in September 2024 and is now adopted by Anthropic, FastHTML and a growing list of e-commerce stores.

Question 2

How does the validator work?

Accepted Answer

You paste any URL. The tool fetches /llms.txt at that host, parses it against the llmstxt.org spec, and runs ~12 checks ranging from critical (file exists, has an H1, contains parseable links) to recommended (blockquote summary, intro paragraphs, optional section) and info-level (file size, content type). Each failed check subtracts points; you get a 0-100 score and an A-F grade. Each failed check also ships a copy-paste-ready markdown snippet that fixes it.

Question 3

Is the tool free?

Accepted Answer

Yes. No account, no email, no rate-limit theatre beyond a fair-use 30 requests per minute per IP. Shipped by BrandUp Factory as a free tool because we also build Index AI, the Shopify app that auto-generates spec-compliant llms.txt files. The validator is useful even if you never install our app.

Question 4

Why should a Shopify store have an llms.txt?

Accepted Answer

Without it, ChatGPT Shopping, Perplexity Buy, Google AI Overviews and Claude have to guess what your store sells by parsing your raw HTML — and they usually get it wrong or skip past your products entirely. A good llms.txt tells those models exactly what you sell, what your policies are, and which collection or product pages to read first.

Question 5

My llms.txt uses plain URLs in lists instead of [label](url) markdown. Is that valid?

Accepted Answer

Technically no — the llmstxt.org spec requires markdown-style hyperlinks `[label](url)` inside list items. In practice, most LLM crawlers still parse plain URLs and we flag this as a warning rather than a critical error. Fixing it is a 2-minute search-and-replace and brings you to spec.

Question 6

Can I share a result?

Accepted Answer

Yes. Every validation result has its own URL — e.g. /tools/llms-txt-validator?url=gymshark.com. Share it on Twitter, LinkedIn or Slack and the social card previews the grade automatically, generated on the fly.

Question 7

Does the validator support sub-paths like /docs/llms.txt?

Accepted Answer

Not yet. We always check the root /llms.txt path because that's where 99% of the use-cases live and what the spec calls out. If you need sub-path validation, drop us a line and we'll add it.

Question 8

Who built this?

Accepted Answer

BrandUp Factory — Shopify Partner agency from Hamburg, Germany. We ship three Shopify apps (Index AI, Product Variants, Section Store). Support: info@brandupfactory.com.

llms.txt Validator

What is llms.txt and why does it matter?

Spec-checked

Shopify-aware

No login