What is llms.txt and why your site probably needs one

An llms.txt file is the equivalent of robots.txt but for language models like ChatGPT, Claude and Perplexity. While robots.txt tells Google what to crawl, llms.txt tells LLMs who you are, what you write about and which pages matter. It is a plain Markdown file that lives at the root of your domain. Think of it as a business card for machines that generate answers. The standard The format was proposed by llmstxt.org in late 2024. It is not official yet. No LLM has publicly confirmed using it. But Anthropic already has one on their own domain. And crawlers from OpenAI, Google and Perplexity already look for similar files when they visit sites. As of mid-2025, fewer than 1,000 domains had published one. Early days. File structure The format is simple Markdown: # Your Site Name > Brief description of your site or project. ## Author - Role: Your role - Experience: Your background - Contact: your@email.com ## Topics Covered - Topic one - Topic two - Topic three ## Content Policy - All conten