Measured 2026-07-09 · 3 of 10 K-beauty export brands block ChatGPT's crawler · 2 are invisible to AI · every number reproducible
HomeGuidesHow to write llms.txt — the cheapest AEO asset, in half a day
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How to write llms.txt — the cheapest AEO asset, in half a day

What llms.txt is, where it goes, and what to put in it so AI reads your brand correctly. Real example, common mistakes, and how to validate it.

llms.txt is a one-page markdown file at your site root. It lets an AI crawler understand who your brand is, what you sell, and which pages to read without wading through hundreds of URLs. It takes half a day and costs nothing — yet when we measured ten K-beauty exporters, not one had it. It is the cheapest and most neglected AEO asset there is.

Where it goes

At the domain root: https://yourbrand.com/llms.txt. It must be the root, not a subpath, because that is where crawlers conventionally look. It is a static file, so no server config is needed — just upload it. Large sites sometimes add an llms-full.txt with the full body text, but it is optional.

What to include — five blocks

The format is simple: an H1 brand name, a one-paragraph summary starting with a blockquote (>), then link lists by section.

BlockContentsWhy
# BrandH1, one lineState the entity name clearly
> Summary2–3 sentences: what you sell, for whomShaped for AI to lift whole
## ProductsKey lines + each URLRoute to pages matching buyer queries
## Key factsVerifiable numbers, certs, originTrust signal and citation material
## ContactEmail, main linksConnect the entity graph

Real example (abridged)

This site's own llms.txt is a live example. The shape is this:

# Acme Cosmetics > A Korean D2C brand making low-irritation skincare for sensitive skin. > Every product is vegan and dermatologist-tested; ships to 30 countries. ## Products - Cica Serum — /products/cica-serum - Panthenol Cream — /products/panthenol-cream ## Key facts - Founded 2018, 1.2M units sold - Dermatest "excellent" grade (2025) ## Contact - hello@example.com

Three common mistakes

1) The summary is a slogan. "A special journey for your skin" gives AI no fact to cite. State what you sell, for whom, and where — as fact. 2) Links point only to the homepage. Link to individual pages that answer buyer queries ("cleanser for oily skin") so you get cited on those queries. 3) Build once, forget. Update it when products or facts change; a wrong llms.txt is worse than none.

Validate it

After uploading, check two things. First, that curl https://yourbrand.com/llms.txt returns the file with a 200. Second, that robots.txt or your CDN is not blocking the path — fetch it with the GPTBot user-agent (see how to check for crawler blocks) and confirm a 200. Pass both and your llms.txt is doing its job.

Next step

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