𝗠𝗮𝘁𝗿𝗔𝗜𝘅 is a population-scale simulated user evaluation infrastructure for testing AI systems and digital products, built by researchers from MIT, Harvard, and Stanford. It simulates the world with 8.3 billion persona agents across 1,290 dimensions and allows companies to run evaluations across various sandbox environments, including surveys, AI chatbots, websites, and apps, in 25+ domains, including e-commerce, finance, gaming, software development, and healthcare.