OpenAI, Google, Microsoft and Anthropic back a shared robots.txt opt-out from AI training

The four companies commit to honoring a new `__usage_ai-training` robots.txt directive, based on an IETF draft by Anthropic's standards lead, that lets publishers block AI training while staying in search. Anthropic already supports it, Microsoft starts on February 1, 2027, Google in early 2027 and OpenAI in the coming months.