Researchers built MatrAIx, a platform that uses 8.3 billion simulated personas to evaluate how AI systems and digital products perform across diverse user types. The system combines human-grounded personas (extracted from Wikipedia, Stack Overflow, surveys) with synthetically generated ones, then runs them through four types of test environments—surveys, chatbots, websites, and apps—to measure how different user groups interact with and respond to products. In validation tests, the simulated personas behaved consistently with their assigned attributes 91.5% of the time, showing this approach can catch user-specific friction points and failure modes faster and cheaper than traditional human testing.