Google, Microsoft, OpenAI and Anthropic support a unified AI training opt-out mechanism

Google, Microsoft, OpenAI and Anthropic announced they will support a unified AI training opt-out signal in robots.txt, so that a website needs only one rule to refuse having its content used for generative AI training. The signal comes from an IETF draft published Friday by Anthropic's Kevin Kelley; websites opt in by adding the policy token __usage_ai-training and listing the paths they do not want used for training. OpenAI plans to implement it within the next few months, Google aims to support it by 2027, and Microsoft will enforce it starting February 1, 2027, replacing the NoArchive and NoCache tags it has used since 2023. The draft states that the signal is only a declaration of content usage preferences rather than a crawling command, and that private agreements between sites and AI companies can override it; the draft was submitted individually, is not endorsed by the IETF, and has no formal status in the standards process.