{
  "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": "2026-03-14",
  "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.",
    "A null citation effect does not mean llms.txt has zero operational value for every workflow. It means the study did not find a measurable citation lift."
  ],
  "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": "Rarely. Only 13.3% of the 37,894 scanned AI-cited domains had an llms.txt file.",
  "answerSummary": "Adoption exists but remains concentrated, indicating that the presence of this file is not a prerequisite for being cited by AI systems.",
  "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": "Operators must allocate technical SEO resources efficiently. Knowing the low adoption rate prevents teams from over-investing in this file at the expense of core content quality and structure.",
  "whatToDo": [
    "Treat llms.txt as an optional housekeeping file rather than a primary citation-growth lever.",
    "Prioritize answer quality, source coverage, and page structure before spending disproportionate effort on llms.txt.",
    "Measure discovery and crawl behavior directly if you publish llms.txt instead of assuming it improves citation performance."
  ],
  "faqs": [
    {
      "question": "How many AI-cited domains actually use llms.txt?",
      "answer": "Out of 37,894 scanned domains, exactly 5,035 domains feature the file."
    },
    {
      "question": "Is an llms.txt file required to get cited by AI engines?",
      "answer": "No. With an adoption rate of 13.3%, the vast majority of cited domains do not use the file."
    }
  ]
}