The llms.txt file is an emerging standard, analogous to robots.txt, designed to help large language models (LLMs) like GPT-4, Claude, and Gemini understand the content and structure of a website. It provides a plain-text or Markdown summary of who you are, what you do, and your key pages — in a format that AI systems can easily parse.
For AEC firms, having an llms.txt file is one of the most forward-looking steps you can take for AI discoverability. As clients increasingly ask AI assistants questions like "Who are the best structural engineers for hospital projects in the northeast?", firms that have helped AI systems understand their specialisms are more likely to be cited.
A well-structured llms.txt for an AEC firm might include: firm name and founding date, primary services and typologies, key completed projects, geographic markets served, notable awards or recognition, and a link to the contact page. The file is placed at the root of the domain: yourfirm.com/llms.txt.
The llms.txt standard was proposed in 2024 and is gaining rapid adoption. While not yet universally supported by all AI systems, early adoption provides a competitive advantage as AI-mediated search becomes mainstream.