What llms.txt actually is
Proposed in 2024 by Jeremy Howard, llms.txt is a markdown file at your site root that lists curated URLs with one-sentence descriptions, intended as an LLM-friendly site map. A companion file, llms-full.txt, expands the markdown summaries into full content excerpts. Neither is a Google ranking factor.
Think of it as a sitemap for assistants: a curated, opinionated guide that points at your highest-value pages with context. Done well, it can influence which pages an LLM crawler prioritises if and when it reads the file.
Who actually consumes it (April 2026)
Public adoption is mixed. Several second-tier agents and developer-focused tools (Cursor, Windsurf, some open-source crawlers) consume llms.txt. The major consumer assistants have not committed publicly, though several engineers from those teams have indicated they are watching adoption.
Realistic expectation: llms.txt is a low-cost insurance policy. It will not produce measurable citation lifts in 2026, and any vendor selling 'llms.txt optimisation' as a primary ranking factor is overstating its current impact.
How to publish a useful one
Keep llms.txt to your top 30–60 most important pages. Group them by category. Write one-sentence descriptions that are genuinely useful — not marketing copy. Include the canonical URL, a short purpose, and a freshness indicator if relevant.
Generate it from the same source of truth as your sitemap so it stays current. We auto-generate ours from the site's content registry; manually maintained llms.txt files go stale within a quarter.