llms.txt
Also known as: llms txt, llms-full.txt
When an AI coding agent tries to help you use a library or API, it pulls from what it learned during training, which may be months or years out of date. llms.txt is a community-driven convention, modeled loosely on robots.txt (the file websites use to tell search engine crawlers what to index), that encourages documentation sites to publish a clean, token-efficient version of their docs that AI tools can retrieve in real time.
The format is simple: a markdown file at yourdomain.com/llms.txt that contains concise, structured documentation for your product, library, or API, written with the assumption that an AI is reading it rather than a human. Some sites also publish an llms-full.txt with the complete reference content, and a condensed version for agents working under tight context budgets.
For builders, llms.txt matters in two directions. When you're building with a framework that publishes one, you can point your coding agent directly at that URL for accurate, current documentation. When you're building a product other developers integrate with AI assistance, publishing llms.txt means their agents get helpful, reliable information about your API instead of hallucinated guesses.