Every website can tell crawlers what they may take. The file that does it is called robots.txt, and until now, telling AI companies “do not train on my site” meant a separate rule for every company. On October 30, 2026, the four big labs agreed to honor one shared signal for training — this builder writes it for you, together with the per-crawler rules that work today. Free, and it runs entirely in your browser: nothing you type is uploaded.
Not sure what the choices mean? There are three different kinds of AI visitor, and blocking each costs something different. Training crawlers collect pages to train models. Search and answer crawlers index pages so AI search can cite them — blocking these can cost you visibility and referrals. User-triggered fetchers visit a page because a person asked an assistant to — blocking them means assistants cannot read your pages for their users.
The shared training signal
Training crawlers — block these from taking my pages for training
Search and answer crawlers — block these and AI search may stop citing you
User-triggered fetchers — block these and assistants cannot open your pages on request
Optional extras
The signal comes from an IETF Internet-Draft dated October 30, 2026, by Anthropic's Kevin Kelley. In your file it looks like this:
User-Agent: __usage_ai-training Disallow: /
The timelines the companies have given: Anthropic has already begun implementing it. OpenAI says “the coming months.” Microsoft starts February 1, 2027. Google aims for 2027, and says it will read a token opt-out as a Google-Extended opt-out where Google-Extended is not named. Two cautions, stated plainly: the draft is an individual submission — not an IETF-endorsed standard — and it expires on May 3, 2027; and a User-Agent: * group does not count, which is why this builder always writes the token as its own group. We checked this claim too — see its Claim Check verdict.
Save it as robots.txt at the root of your domain, so it answers at https://yoursite.com/robots.txt. If you already have a robots.txt with rules for other bots or paths, merge — do not replace blindly: keep your existing groups and add the groups this builder made. Then visit your own /robots.txt address to confirm it is live, and re-check it after any site redesign.
For the record, bizn.org's own choice is the opposite of most of these settings: our robots.txt allows every crawler, because this site is built to be read by agents as well as people. Your site, your call — this builder exists so the call is yours to make, in one sitting, without learning the syntax.