Google, Microsoft, OpenAI and Anthropic back one AI training opt-out in robots.txt

Four major AI companies—Google, Microsoft, OpenAI, and Anthropic—have agreed to honor a shared opt-out mechanism for AI training data via the robots.txt standard. This means website owners can use a single robots.txt directive to prevent their content from being used to train models from all four companies. The move represents a rare cross-industry alignment on data governance for AI training.