llms.txt specification (llmstxt.org)

The proposal page for the /llms.txt standard — the primary spec behind the llms-txt page.

Key facts

Author and date. Proposed by Jeremy Howard (fast.ai), published September 3, 2024.
Location. A markdown file at the site root path /llms.txt (optionally in subpaths).
Required structure, in order: (1) an optional byte-order mark; (2) an H1 with the project/site name — the only required section; (3) a blockquote with a short summary; (4) zero or more markdown sections (paragraphs, lists) of detail; (5) zero or more H2-delimited sections containing file lists.
File-list format. “Each ‘file list’ is a markdown list, containing a required markdown hyperlink [name](url), then optionally a : and notes about the file.”
The “Optional” section. A reserved H2 whose links “can be skipped if a shorter context is needed … Use it for secondary information which can often be skipped” — the spec’s built-in priority lever for tight context windows.
Not formally specced: the page does not define an llms-full.txt companion; it cites FastHTML’s llms-ctx.txt / llms-ctx-full.txt only as an implementation example.

T1 — the primary specification document itself.