llms.txt Checker
Validate in 90 seconds.
Only 6.9% of sampled websites publish llms.txt. CiteFuel validates the proposed format and linked URLs and can generate a clean replacement. The file is optional, and the result is not a Google ranking or AI-citation guarantee.
Queued…
What we check
11 checks. One valid file.
A malformed llms.txt scores lower inside CiteFuel's optional file-hygiene check because dead links and invalid structure reduce its usefulness to any compatible service. CiteFuel does not treat that internal result as evidence of an external ranking or citation penalty. The validator checks:
- ✓ File present at correct root path
- ✓ Valid Markdown structure (H1, blockquote, sections)
- ✓ All linked URLs return HTTP 200
- ✓ No invented or stale entries
- ✓ Description and heading structure
- ✓ Safe absolute-URL formatting
- ✓ Optional llms-full.txt reference
If your llms.txt fails a check, CiteFuel can generate an optional proposal-format draft from the audited sitemap. Review every URL before publishing; a passing file does not prove engine adoption.
What valid llms.txt looks like
# Acme Robotics
> Acme builds warehouse robotics
> for mid-market 3PLs in North America.
## Pages
- [Pricing](https://acme.com/pricing): Plans for teams of all sizes
- [API Docs](https://acme.com/docs): REST + webhook reference
- [Case Studies](https://acme.com/proof): Customer results
## About
- [About Acme](https://acme.com/about): Founded 2021, 40-person teamDraft URLs come from the submitted sitemap; linked-page reachability and content are not independently verified.
The llms.txt landscape — 10,000 sites, June 2026
Most sites do not publish this proposed file.
llms.txt adoption rate
In a CiteFuel crawl study of 10,000 Tranco-ranked domains, only 6.9% had any llms.txt at all — and just 1.5% had a complete llms-full.txt companion. These figures measure adoption only; they do not establish a citation or ranking advantage.
Sites publishing all five measured configuration items
Across five technical checklist items (llms.txt, Organization schema, robots.txt AI policy, canonical tags, and HTTPS), only 2.9% of sites hit all five. This is an internal readiness benchmark, not evidence that each item is a ranking lever.
Median TTFB for sites with llms.txt
In this sample, sites with a valid llms.txt had a 203ms median Time to First Byte versus 255ms for sites without one. This was a correlation, not evidence that llms.txt improved performance; other site or team characteristics may explain the difference.
Source: CiteFuel 10,000-domain crawl study, June 2026 · Methodology
What llms.txt does — and does not do
A voluntary site map for services that support it.
The llms.txt proposal was introduced in late 2024 as a concise Markdown map of important site pages. Unlike robots.txt, it does not control crawler access. A compatible service may choose to read it, but publishers cannot require an engine to honor it.
CiteFuel has not established that ChatGPT, Claude, or Perplexity use llms.txt as a ranking or citation signal. Google Search explicitly says it ignores the file, including for its generative AI features, so publishing one neither helps nor hurts Google visibility. Normal crawlability, indexability, helpful content, and independent authority remain the durable priorities.
The most common failure modes CiteFuel finds: llms.txt missing entirely, llms.txt present but with dead links (URLs that return 404), llms.txt that lists pages not in the sitemap (invented content), and description blockquotes that are truncated or empty. These defects make the optional document less reliable for services that choose to consume it; they are not proof of a ranking or citation penalty. CiteFuel's 11-check validator flags syntax and structure issues and can generate a reviewable draft from your submitted sitemap.
For a deeper guide to llms.txt format and best practices, see How to Add llms.txt to Your Website. For the broader picture of AI crawlability — beyond llms.txt to robots.txt, schema, and passage structure — see AI Crawlability Checker and CiteFuel's full methodology.
Frequently asked questions
What is an llms.txt file?
llms.txt is a proposed, voluntary Markdown file placed at the root of a website (for example, https://yourdomain.com/llms.txt). It can provide a curated map of important pages to services that choose to consume it. Adoption by major answer engines is not established, and Google Search explicitly ignores llms.txt, so the file does not help or hurt classic Google rankings, AI Overviews, or AI Mode.
Does my site need an llms.txt to be cited by AI?
No. A site can be crawled, indexed, ranked, and cited without llms.txt. CiteFuel checks the file as an optional interoperability and documentation artifact, not as proof of ranking or citation eligibility. Our crawl study found 6.9% adoption in the sampled domain set; that measures publication of the file, not a visibility advantage. Google Search says it ignores llms.txt.
What does CiteFuel's llms.txt checker look for?
CiteFuel runs 11 syntax and format checks, including root-path presence, Markdown structure (H1, blockquote description, sections), and safe absolute URL formatting. The generator uses URLs found in the submitted sitemap and derives labels from URL slugs; it does not fetch every linked page, verify reachability, judge description quality, or prove consumer adoption. Review the draft before publishing.
What is the difference between llms.txt and llms-full.txt?
llms.txt is a concise, structured site summary for services that support the proposal. llms-full.txt is an optional companion containing fuller page content. Neither file is required by Google Search, and CiteFuel does not claim that either one improves rankings or citations.
How often should I update my llms.txt?
If you choose to maintain llms.txt, update it when important URLs change. Dead links make the file less useful to any compatible service, but CiteFuel has not established that a stale file causes a citation penalty. CiteFuel's $9/mo re-audit subscription can monitor the file for drift and malformed or dead entries.
Can I check my llms.txt without running a full audit?
Yes. CiteFuel's free audit includes llms.txt presence and validation as part of its 26-check sweep. You can also use the standalone llms.txt Validator + Generator tool to check or generate your file independently, without running the full audit.
Related tools
llms.txt Validator + Generator
Validate an existing file or generate one from your sitemap — standalone, no full audit required.
AI Crawlability Checker
Check if AI crawlers can actually read your pages — robots.txt, rendering, schema, and passage access.
AI Crawler Access Checker
See exactly which of 14 AI user-agents your robots.txt blocks, with a targeted fix block to paste in.
Check your llms.txt — free, no card, 90 seconds.
CiteFuel validates 11 file-hygiene checks and can generate an optional proposal-format draft for review.
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