Who Actually Publishes an llms.txt? We Checked 44 Top AI Tools
The llms.txt standard is pitched as the robots.txt of the AI era: one curated Markdown file that tells ChatGPT, Claude and Perplexity which pages on your site matter most. Everyone is talking about it. So we fetched the live /llms.txt of 44 leading AI and SaaS tools to see who has actually shipped one. A slim majority now have, but a surprising number are stubs or data dumps rather than the curated maps the standard intends.
Key findings
- 25 of 44 tools (57%) publish a valid
llms.txtonce you follow redirects, a slim majority. The other 43% return a 404, redirect away, or serve an HTML page where the file should be. - But only 21 are actually curated maps. The remaining adopters ship a near-empty stub or a giant unstructured dump (one is over 500 KB with zero curated links), which is not what the standard is for.
- The full-text companion is rare. Just 5 of the 25 adopters also serve an
llms-full.txt(20% of adopters). - Size varies by more than 200x. Mailchimp serves a 512.5 KB file with 0 links, while Shopify ships just 0.8 KB, so there is still no shared convention for how big or detailed the file should be.
The headline: a slim majority, but quality is all over the place
For all the noise about llms.txt being the next essential AI-SEO file, adoption among the tools that would benefit most is only a slim majority: 25 of the 44 well-known AI and SaaS tools we checked (57%) serve a valid one once redirects are followed. The other 43% either have not created the file, redirect the request somewhere else, or return their normal HTML app shell at /llms.txt, which is worse than nothing because an AI client fetching that URL just gets a page of markup. And "has one" is not the same as "did it well": only 21 of the 25 adopters ship a genuinely curated map. The rest range from a sub-1 KB stub to a 500 KB dump with no curated links. The takeaway for a small site is encouraging: a clean, curated, valid llms.txt still puts you ahead of most of the market, at essentially zero cost.
The 25 tools that publish a valid llms.txt
These are the tools whose /llms.txt returned a real Markdown file, sorted by size. The links column counts curated Markdown links in the file (a rough proxy for how much of the site it maps), and the last column shows whether the tool also serves the heavier full-text llms-full.txt.
| Tool | File | Size | Links | llms-full.txt |
|---|---|---|---|---|
| Mailchimp | mailchimp.com/llms.txt | 512.5 KB | 0 | No |
| Vercel | vercel.com/llms.txt | 186.8 KB | 1660 | No |
| Writesonic | writesonic.com/llms.txt | 113.5 KB | 455 | No |
| Stripe | stripe.com/llms.txt | 62.7 KB | 268 | No |
| Slack | slack.com/llms.txt | 39.7 KB | 165 | No |
| Wix | wix.com/llms.txt | 35.2 KB | 131 | No |
| Cloudflare | cloudflare.com/llms.txt | 16.5 KB | 88 | Yes |
| Calendly | calendly.com/llms.txt | 14.8 KB | 52 | No |
| Semrush | semrush.com/llms.txt | 14.6 KB | 42 | No |
| Webflow | webflow.com/llms.txt | 13.0 KB | 75 | No |
| Jasper | jasper.ai/llms.txt | 12.0 KB | 61 | No |
| Zapier | zapier.com/llms.txt | 11.1 KB | 16 | Yes |
| Monday.com | monday.com/llms.txt | 9.7 KB | 53 | No |
| ElevenLabs | elevenlabs.io/llms.txt | 9.2 KB | 47 | No |
| ClickUp | clickup.com/llms.txt | 8.6 KB | 50 | Yes |
| Pictory | pictory.ai/llms.txt | 8.6 KB | 78 | No |
| HeyGen | heygen.com/llms.txt | 8.5 KB | 44 | Yes |
| Notion | notion.so/llms.txt | 6.8 KB | 49 | No |
| Descript | descript.com/llms.txt | 6.2 KB | 42 | No |
| Asana | asana.com/llms.txt | 5.6 KB | 44 | No |
| beehiiv | beehiiv.com/llms.txt | 5.5 KB | 45 | Yes |
| Gamma | gamma.app/llms.txt | 4.2 KB | 29 | No |
| Squarespace | squarespace.com/llms.txt | 2.0 KB | 0 | No |
| Loom | loom.com/llms.txt | 0.9 KB | 0 | No |
| Shopify | shopify.com/llms.txt | 0.8 KB | 9 | No |
The 16 that do not have one yet
At fetch time these tools returned a 404, a redirect that did not land on a valid file, or an HTML page at /llms.txt: Ahrefs, Airtable, Anthropic / Claude, ConvertKit / Kit, Copy.ai, Fathom, Figma, Grammarly, HubSpot, Miro, Otter.ai, Runway, Substack, Surfer SEO, Synthesia, Trello. A further 3 (OpenAI / ChatGPT, Perplexity, Canva) returned a block or error at fetch time and could not be confirmed either way. A redirect or an app shell in that slot is a missed opportunity: it is the one URL an AI client will try, and it should return a curated Markdown map or a clean 404, not a rendered page.
https://[domain]/llms.txt for 44 well-known AI and SaaS tools, following redirects. A tool is counted as publishing a valid llms.txt only when the response is HTTP 200 and the body is plain-text Markdown whose first non-empty line is a heading (#) or a summary blockquote (>), matching the llms.txt specification. Responses that are HTML pages, SPA soft-404s, empty, or redirect to unrelated URLs are counted as not having one. For each valid file we then checked /llms-full.txt the same way. llms.txt is an emerging convention, files change, and a domain can add or remove one any day, so this is a snapshot, not a verdict on any company. Want to see a working example? We publish our own at /llms.txt.
Cite this study
This is free, original research under a CC BY 4.0 license. Use any figure on your own site with a link back, and copy the citation below.
AI Tools Insider (2026). llms.txt Adoption Among 44 Top AI Tools. Retrieved from https://aitoolsinsiderhq.com/ai-llms-txt-study.html
Can AI engines actually read your site?
An llms.txt is only half the picture; the other half is whether the citation crawlers that feed ChatGPT and Perplexity are even allowed in. Check your own site with our free AI Crawler & robots.txt Access Checker and read the companion study on who blocks ChatGPT, Claude and Perplexity.
Serious about AI-search visibility across a real site? Semrush is the all-in-one suite we use to track rankings and technical SEO, and it now reports on AI Overviews too.
That Semrush link is an affiliate link; it costs you nothing extra and we only run it on tools we use ourselves.
Questions about llms.txt
What is llms.txt?
A proposed standard: a plain-text Markdown file at /llms.txt that gives large language models a clean, curated map of a site's most important pages, so an AI assistant can find and cite the right content without parsing rendered HTML. A companion /llms-full.txt inlines the full text of those pages.
How many top AI tools publish one?
Of the 44 leading AI and SaaS tools we checked in July 2026, only 25 (57%) served a valid llms.txt. The other 43% return a 404, redirect away, or serve HTML where the file should be.
Does llms.txt help AI search visibility?
Adoption is early and no major AI engine has publicly confirmed it as a ranking input, so treat it as a low-cost, forward-looking signal, not a guaranteed win. It is cheap, it cannot hurt, and it forces you to name your most citable pages. The bigger lever today is not blocking citation crawlers like OAI-SearchBot and PerplexityBot in robots.txt.
How do I create one for my own site?
Start with an # H1 title, a one-line > summary, then Markdown sections of your key links as - [Title](URL): short description. Keep it curated, not a full sitemap, and save it as llms.txt at your domain root. Ours lives at /llms.txt as a working example.
More on AI search visibility
See whether ChatGPT and Perplexity can actually read your pages, or browse the free tools we built for AI-search optimization.
Part of AI Tools Insider Research, our independent data studies on the AI tools industry.