[DEVELOPING] Google, Microsoft, OpenAI, Anthropic back one robots.txt AI-training opt-out; Bing adds grounding control
On Oct 30, Google, Microsoft, OpenAI and Anthropic said they will honor one robots.txt token, __usage_ai-training, from an individual IETF draft that has no formal standards status. Microsoft also added a separate page-level AI Grounding preference that controls whether a page can feed AI answers in Bing, Copilot and Microsoft 365. It defaults to Allow, and Microsoft says 'neither choice guarantees inclusion, traffic, or payment.' Google says it will treat a token opt-out as a Google-Extended disallow. PPC Land notes this also removes a site from grounding in Gemini Apps and Vertex AI, while AI Overviews and AI Mode stay under Googlebot controls. What to watch: Bing Webmaster Tools transition settings open on Dec 15, Microsoft starts enforcing on Feb 1, 2027, Google targets 2027, and OpenAI says 'the coming months.' Per PPC Land, Meta, Amazon and Apple have not committed.