{
  "kind": "answer",
  "studySlug": "llmstxt-effect",
  "slug": "how-common-is-llms-txt-on-ai-cited-domains",
  "title": "How common is llms.txt on AI-cited domains?",
  "description": "It is still uncommon. Only 13.3% of the 37,894 scanned AI-cited domains had an llms.txt file.",
  "lastUpdated": "2026-09-04",
  "lastTested": "2026-03-14",
  "sourceStudyUrl": "/trakkr-research/llmstxt-effect",
  "sourceStudyTitle": "The llms.txt Effect",
  "claimIds": [
    "llmstxt-effect:domains",
    "llmstxt-effect:adoption",
    "llmstxt-effect:with-file"
  ],
  "relatedSlugs": [
    "answer:is-llms-txt-more-common-on-top-domains-than-the-long-tail",
    "answer:which-industries-adopt-llms-txt-most",
    "fact:median-citations-are-identical-with-and-without-llms-txt",
    "tracker:llmstxt-adoption-by-sector-tracker"
  ],
  "methodologySummary": "Built from HTTP scans of 37,894 AI-cited domains, linked to 337,362 citations and 882 citation snapshots in the Trakkr corpus.",
  "limitations": [
    "This is an observational study. It measures correlation with citation outcomes, not a controlled experiment.",
    "Adoption is uneven by sector, so raw averages can hide category concentration in SaaS and developer tooling.",
    "The top-5,000 test returns p=0.85. The full scanned sample returns p<0.001 with reported r=-0.065. Neither establishes a causal effect. The public aggregates do not include confidence intervals or document the cohort for citation means and medians well enough to recompute the tests."
  ],
  "keywords": [
    "llms.txt",
    "llms txt effect",
    "AI citations",
    "does llms.txt work",
    "llms.txt adoption",
    "how many sites have llms.txt"
  ],
  "schemaHints": {
    "pageType": "Article",
    "includeDataset": true
  },
  "question": "How common is llms.txt on AI-cited domains?",
  "directAnswer": "It is still uncommon. Only 13.3% of the 37,894 scanned AI-cited domains had an llms.txt file.",
  "answerSummary": "Adoption exists, but it is nowhere close to universal and remains concentrated in specific sectors.",
  "keyFacts": [
    {
      "label": "Domains scanned",
      "value": "37,894",
      "detail": "AI-cited domains scanned for llms.txt.",
      "claimId": "llmstxt-effect:domains"
    },
    {
      "label": "Adoption rate",
      "value": "13.3%",
      "detail": "Domains with llms.txt in the study.",
      "claimId": "llmstxt-effect:adoption"
    },
    {
      "label": "Domains with llms.txt",
      "value": "5,035",
      "detail": "Absolute adoption count.",
      "claimId": "llmstxt-effect:with-file"
    }
  ],
  "evidenceTable": [
    {
      "label": "Domains scanned",
      "value": "37,894",
      "note": "AI-cited domains scanned for llms.txt."
    },
    {
      "label": "Adoption rate",
      "value": "13.3%",
      "note": "Domains with llms.txt in the study."
    },
    {
      "label": "Domains with llms.txt",
      "value": "5,035",
      "note": "Absolute adoption count."
    }
  ],
  "whyItMatters": "This answer matters because it turns a study finding into an operating rule teams can use when they decide what to publish, refresh, or measure next.",
  "whatToDo": [
    "Treat llms.txt as an optional housekeeping file, not a primary citation-growth lever.",
    "Prioritize answer quality, source coverage, and page structure before spending disproportionate effort on llms.txt.",
    "If you do publish llms.txt, measure discovery and crawl behavior directly instead of assuming it improved citation performance."
  ],
  "faqs": [
    {
      "question": "How common is llms.txt on AI-cited domains?",
      "answer": "It is still uncommon. Only 13.3% of the 37,894 scanned AI-cited domains had an llms.txt file."
    },
    {
      "question": "Which numbers from The llms.txt Effect matter most here?",
      "answer": "Domains scanned: 37,894. AI-cited domains scanned for llms.txt. Adoption rate: 13.3%. Domains with llms.txt in the study."
    },
    {
      "question": "What should a team do next?",
      "answer": "Treat llms.txt as an optional housekeeping file, not a primary citation-growth lever. Prioritize answer quality, source coverage, and page structure before spending disproportionate effort on llms.txt. If you do publish llms.txt, measure discovery and crawl behavior directly instead of assuming it improved citation performance."
    }
  ]
}