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AI visibility

What is llms.txt and do I need one

It is a short markdown file describing what your product is and pointing at the pages worth reading, written for models rather than crawlers. Adoption is early and support is not universal, so this is an edge rather than a requirement — but it costs ten minutes.

What 13x checks

This is rule aeo.llms-txt in the public registry: llms.txt is present. It runs on every audit, against the pages we actually fetched, and its result is derived from the response rather than estimated.

Surface
AI visibility
Score weight
4 of the readiness score
Scope
Runs on every audited page
Applies
To every site

Registry version 2026-07-30. Every rule is published, and the audit is deterministic — the same page produces the same finding every time.

The fix

The same text the audit hands you when this check fails on your own site.

Add /llms.txt — a short markdown file describing your product for models rather than crawlers:

Configuration
# example.com

> One sentence saying what this is and who it is for.

## What it does

- Capability one, stated plainly
- Capability two

## Key pages

- [Pricing](https://example.com/pricing): what each plan includes
- [Docs](https://example.com/docs): how to get started

## Contact

hello@example.com

Serve it as text/plain or text/markdown from the web root. Adoption is early and not universally honoured, so treat this as cheap upside rather than a requirement.

Framework-specific versions

Where the change differs enough to be worth writing out separately.

Does your site have this problem?

13x checks this and 112 others against your live URL in about 30 seconds. No account, and every finding comes with the fix for your framework.

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