Off-Page Signals Have Model-Specific Effects on Generative AI Search Visibility: Evidence from a Cross-Platform Audit of 2,729 Businesses Across Five Generative AI Systems

Background. Businesses are increasingly discovered through generative artificial intelligence (AI) search systems such as ChatGPT, Claude, Perplexity, Google Gemini, and Google AI Overviews. The off-page signals that drive whether a business appears in those answers are not well characterised, and prior work has typically aggregated outcomes across models, masking model-specific behaviour. Methods. We audited 2,729 businesses across 14 verticals and four metropolitan markets (Los Angeles, New Yo