Quick answer
llms.txt is an optional, plain-text proposal for giving AI tools a concise map of a site’s useful resources. NOTABIS records llms-txt-accessible when a GET request to /llms.txt returns a response below the HTTP error range. This is an availability measurement, not a Google requirement, ranking signal, or guarantee that an AI system will read the file.
What the issue means
An llms.txt file can describe a site, link to important pages, and point readers toward fuller documentation. It is separate from robots.txt, which controls crawler access, and from a sitemap, which lists URLs for discovery. The proposal has no universal search-engine or AI-platform implementation contract, so content should remain useful as ordinary public documentation.
Why it matters for SEO
There is no established evidence that publishing llms.txt improves Google rankings or indexing. A clear resource list can help a human or compatible tool understand a site, but it does not replace HTML content, internal links, canonical signals, or a sitemap. NOTABIS keeps the result in site-health diagnostics rather than the SEO score.
How NOTABIS detects it
At the start of an audit, after fetching robots.txt, NOTABIS requests the origin’s /llms.txt. If the final response status is below 400, it records a passed llms-txt-accessible check and stores the status, content type, and byte count in diagnostics. It does not validate the file’s syntax, recommendations, links, or usefulness.
How to check it yourself
Request the public file and inspect the final response:
curl -sS -D - https://example.com/llms.txt -o llms.txt
Get-Content .\llms.txt
Check that the file is plain text, links to public pages, contains no secrets, and remains readable without a login or challenge. Review access logs if an AI tool or documentation consumer is expected to use it.
How to fix it
Publish a short, maintained file only when it serves a clear documentation or AI-discovery purpose. Link to canonical public pages, label drafts and deprecated resources, and keep the file consistent with the site’s navigation. Return a successful response at /llms.txt, preserve the content type through the CDN, and rerun the audit after deployment.
When this is intentional or does not need fixing
Most sites do not need an llms.txt file. A missing file is not an SEO defect, and a private site should not expose internal URLs to satisfy an optional convention. Do not create one from unreviewed generated text or imply that it controls how an AI system uses your content.
Related issues
Compare optional llms.txt availability, robots.txt availability, and sitemap access.
Run a NOTABIS audit
NOTABIS records whether /llms.txt was reachable and reports the response evidence without treating this optional resource as an SEO score factor.