robots.txt: the standard for crawl control
robots.txt has governed crawler behaviour for decades. It is a plain text file at your site root containing allow and deny rules that compliant crawlers read before fetching pages. It works just as well for AI crawlers as for search engines: you can Disallow GPTBot, ClaudeBot, CCBot, Google-Extended, PerplexityBot, and others by name to keep them off your content.
Crucially, robots.txt is a request, not a wall. Well-behaved crawlers honour it; it controls crawling rather than enforcing access. That makes it the right tool when your goal is to keep specific bots away from your pages, especially AI scrapers gathering training data. A manager like robot.guard keeps a curated, maintained list of those AI crawlers so you can block them without hunting down user-agent strings yourself.
llms.txt: an optional convention for AI visibility
llms.txt, proposed at llmstxt.org in 2024, is a newer and entirely optional convention. It is a curated markdown file that summarises your site and links to your most important content in a clean, easily parsed form. The idea is to help large language models and answer engines find and understand the parts of your site that matter, rather than guessing from cluttered HTML.
Importantly, llms.txt is not an access-control mechanism. It does not block anything; it has no Disallow equivalent. It is guidance for visibility, aimed at the AI systems you want representing your content well. Adoption is still emerging and no engine is required to read it, so treat it as an opportunity to present yourself clearly rather than a control you can rely on.
Do you need both? Usually yes — for different reasons
Because the two files do different jobs, most sites benefit from both. Use robots.txt to draw the line: block the AI crawlers you do not want anywhere near your content, and allow the search and social bots you depend on. This is your enforcement layer, the one that actually keeps unwanted crawlers out (insofar as they comply).
Then, optionally, add an llms.txt to better present yourself to the AI engines you are happy to be cited by. There is no conflict between the two — blocking a bot in robots.txt and guiding the rest in llms.txt are complementary moves. Start with robots.txt, which you can build and download in robot.guard, and layer llms.txt on top once your blocking rules are in place.
robots.txt vs llms.txt at a glance
| robots.txt | llms.txt | |
|---|---|---|
| Purpose | Control which crawlers may fetch your pages | Help AI engines understand and surface your content |
| Format | Plain text with allow/deny rules | Curated markdown summary with links |
| Blocks crawlers? | Yes — Disallow keeps compliant bots out | No — it is guidance, not a gate |
| Who reads it | Search, social, and AI crawlers | AI and answer engines (where supported) |
| Status | Long-standing, widely respected standard | Newer, optional convention; adoption still emerging |
frequently asked
- Does llms.txt block AI bots from using my content?
- No. llms.txt is not an access-control file and has no blocking directives. It only helps AI engines understand your site. To block AI crawlers you need robots.txt, where you can Disallow bots like GPTBot, ClaudeBot, and CCBot by name.
- If I have robots.txt, do I still need llms.txt?
- They serve different goals. robots.txt blocks the crawlers you do not want; llms.txt helps the AI engines you do want present your content accurately. If you care about how answer engines represent you, llms.txt is a useful optional addition — but it is not a replacement.
- Will AI engines actually read my llms.txt?
- Maybe. llms.txt is an emerging convention from llmstxt.org and no engine is required to support it, so adoption is still uneven. Treat it as an opportunity to present your site clearly rather than a guarantee, and rely on robots.txt for anything you need enforced.
- Can I block AI training but still allow answer engines?
- Yes — that is exactly what robots.txt is for. You can Disallow training-focused crawlers like GPTBot and CCBot while allowing others, and a tool like robot.guard keeps the current AI user-agent list curated so your rules stay accurate over time.
Last updated June 9, 2026