Anthropic and Microsoft join the shared robots.txt opt-out from AI training

Anthropic and Microsoft have joined Google and OpenAI in backing one shared robots.txt signal that lets a website tell several AI companies at once not to train on its content, Nieman Lab reports. The signal was proposed by Anthropic engineer Kevin Kelley as part of work at the Internet Engineering Task Force (IETF), and Anthropic is backing it. Timing differs by company: OpenAI says it will support it in the coming months, while Google and Microsoft say next year. We covered Google and OpenAI's plans on 31 October; new here are the two extra companies and their timelines, and Meta's communications chief Andy Stone called the signal "an important step".