Why Your Site Should Have an llms.txt

llms.txt is the AI-era counterpart to robots.txt. It is a single Markdown file at the root of your domain (e.g., https://yourcompany.com/llms.txt) that tells large language models how to interpret and cite your site. It is unofficial, fast-spreading, and increasingly respected by the major AI search surfaces.

The file should include: a one-sentence company summary, a clear positioning statement, your ICP definition, your most authoritative pages (with URLs and short descriptions), your machine-readable endpoints (profile.json, openapi.json, etc.), and a brief contact note. Keep it under 200 lines. Update it every quarter.

The reason llms.txt matters is that AI models are increasingly synthesizing answers from multiple sources. Without a single source-of-truth file, the model triangulates from your homepage, product pages, and third-party mentions, and often gets you wrong. With llms.txt, the model has one canonical reference and is far more likely to cite you accurately.

If you do nothing else for GEO this quarter, publish an llms.txt. It costs nothing, takes an afternoon, and meaningfully shifts how AI assistants describe and recommend you. The companies that did this in 2024-2025 are already showing up in ChatGPT shortlists. The rest are catching up.