AI coding glossary
llms.txt
Also known as: llms.txt file, ai readme
In one sentence
A plain-text file at a site's root that gives AI clients (ChatGPT, Claude, Perplexity) a curated map of the site's most useful pages, in a format LLMs can ingest cheaply.
Full definition
llms.txt is a community standard for making a website navigable by AI clients. The file lives at /llms.txt and lists the site's most important pages as Markdown links with one-line descriptions. AI clients use it as a discovery shortcut, instead of crawling the full sitemap, they read llms.txt for the curated overview. The companion /llms-full.txt extends the same idea with longer copy. Adopted by Anthropic, Vercel, Stripe, skills-hub.ai, and a growing set of dev-tools sites in 2026, it's the modern equivalent of robots.txt, but for AI clients rather than search engine crawlers.