https://citationexperiments.com/ I test what gets cited in AI answers, and publish the results. https://citationexperiments.com/geo-landscape.html The data behind generative engine optimization: market size, AI search adoption, and the collapse of the click. 2026-10-18 https://citationexperiments.com/the-sign-in-wall.html Perplexity and Copilot now require sign-in before showing any answer. What the guest-access shutdown means for citation research. 2026-10-18