What is llms.txt, and is it worth adding?

llms.txt is a plain-text file at the root of your domain that describes your site for language models. Same location convention as robots.txt, entirely different job.

robots.txt says who may fetch what.
sitemap.xml says which URLs exist.
llms.txt says what this site is, in your own words.

Why it exists

A model that lands on your homepage has to reconstruct what you do from navigation, marketing copy and whatever HTML survived the build. It gets pricing from a table it may misread, and your product category from a headline written to sound clever rather than to be precise.

llms.txt replaces that reconstruction with a statement. You write the summary; the model does not have to guess it.

What belongs in it

Keep it short and factual. Markdown, served as text/plain.

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Two rules that matter more than the format:

Prices as numbers. "Affordable" is unusable. "49 EUR per month" can be quoted.
No marketing adjectives. Anything a competitor could also write about themselves is wasted space.

A longer llms-full.txt with your full content is a useful companion — it lets an agent answer detail questions without a second request.

The soft 404 trap

The most common mistake is not a missing file. It is a file that appears to exist.

Many frameworks answer unknown paths with the app shell and a 200 status. Request /llms.txt and you get HTML, a text/html content type, and a status that says everything is fine. To a crawler that is indistinguishable from a broken file, and you will never notice by clicking the link in a browser.

Check the content type, not just the status code:

curl -sI https://example.com/llms.txt | grep -i content-type

If that says text/html, your llms.txt does not exist as far as any consumer is concerned.

Is anything actually reading it?

Honest answer: adoption is uneven, and no major model provider has committed to it publicly. If you are looking for a guaranteed ranking effect, this is not it.

The case for adding it anyway is cheaper than the debate: it is one static file, it takes twenty minutes, and it forces you to write down what your product is in plain language — which turns out to be useful for your own homepage too. The downside risk is a file nobody fetches.

Not sure whether yours is a real file or a soft 404? Run a free scan — five checks, under 60 seconds, no login.

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