Comparison
ai.txt vs llms.txt: what is the difference?
ai.txt proposals are about AI usage permissions — signaling whether your content may be used for AI training (an opt-out idea). llms.txt is a curated content map that points assistants to your best pages. One is about permission; the other is about guidance. Neither is a formally adopted web standard.
Different jobs
- ai.txt: express AI training/usage permissions (opt-out signaling). Overlaps conceptually with robots.txt AI tokens.
- llms.txt: a concise Markdown map of your strongest source pages for assistants to read.
Which should you publish?
- For permissions: robots.txt with AI tokens (GPTBot, Google-Extended, etc.) is the widely-honored mechanism today; ai.txt is not broadly enforced.
- For guidance: publish llms.txt as a curated source map.
- Reality check: neither is guaranteed to be consumed; fundamentals (crawlable, quotable pages) matter more.
Related pages: llms.txt vs robots.txt, llms.txt vs llms-full.txt, should I allow GPTBot.