llms.txt is an emerging standard for declaring to AI agents which URLs on a site contain the most important content for them to read. It is conceptually similar to robots.txt and sitemap.xml but written in clean markdown with one URL per line under topical headings. The file sits at the root of the domain at /llms.txt.
AI agents prefer clean, structured, markdown-formatted sources over crawling rendered HTML. llms.txt gives them a curated index of the brand's canonical pages. Sites publishing llms.txt give themselves an outsized chance of being read deeply by the agents that crawl them.
A short brand description, then sections of URL bullets grouped by topic (services, products, blog, contact). The file is human-readable and machine-parseable. Spacemen Digital's example is at /llms.txt.
Write the file in markdown. Place at the site root so the URL is /llms.txt. Reference companion llms-full.txt for long-form brand information. Spacemen Digital ships llms.txt for clients as part of every AEO retainer and includes the check in the free Website AI Agent Readiness Check.
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