What is llms.txt?

The llms.txt standard emerged in late 2025 as a way for website owners to proactively guide AI search engines. Similar to how robots.txt tells crawlers what to access, llms.txt tells AI systems what your site is about and which pages matter most. The file is served at the root path (/llms.txt) in plain text format with a structured markdown-like syntax. It typically includes: a brief site description, sections listing key product pages, blog content, resources, company information, and important facts about the brand. While not yet a formal standard, major AI platforms including ChatGPT and Perplexity have begun respecting llms.txt files. For SaaS companies, maintaining an up-to-date llms.txt ensures that AI search engines accurately represent your product capabilities and direct users to the most relevant pages.