The $2B AI Startup Simulating Human Behavior with 85% Accuracy
What if AI could predict human behavior before it happens? I sat down with Joon Sung Park, Co-Founder & CEO of Simile, the $2B AI startup building foundation models of human behavior, backed by Greenoaks, Index Ventures, + investors including Fei-Fei Li & Andrej Karpathy. Simile is building digital twins of real people to simulate how individuals, consumers, and entire populations make decisions. Its foundational Stanford research demonstrated 85%+ accuracy in predicting human behavior, and today the company has partnerships providing access to over 40 million real people globally. Companies including CVS, Wealthfront, Deloitte, and Banco Itaú are already working with Simile to understand their customers, test products, optimize messaging, and simulate decisions before deploying them in the real world. We discuss how Joon's original Stanford research, Smallville, evolved from 25 autonomous AI agents into a $2B company, why human behavior is more predictable than we think, and how simulations could transform traditional market research, corporate strategy, and decision-making. We also put Simile to the test. Before our interview, Joon simulated our conversation using AI, and the model correctly anticipated one of my opening questions. Joon Sung Park: https://x.com/joon_s_pk Molly O’Shea: https://x.com/MollySOShea Sourcery: https://x.com/sourceryy 𝐄𝐏𝐈𝐒𝐎𝐃𝐄 𝐋𝐈𝐍𝐊 YouTube: https://youtu.be/-6Kg5N7JL7I 𝐒𝐏𝐎𝐍𝐒𝐎𝐑𝐒 • Brex—The modern finance platform, combining the world’s smartest corporate card with integrated expense management, banking, bill pay, & travel. https://brex.com/sourcery • Harvey—The AI platform built for legal work, is helping the best firms and companies close deals faster. More than 200,000 lawyers, 80% of the Am Law 100, and over 20% of the Fortune 500 build with Harvey. Visit: http://harvey.ai/ • Zone—develops next-generation data center campuses, partnering with AI companies, site developers and technology leaders to bring compute online faster and at scale. Visit: https://zonefrontier.com • Mercor—The human intelligence behind frontier AI. Frontier labs and leading enterprises use Mercor to turn the knowledge of 5M+ experts into the data, evals and benchmarks that make AI better at real work. Visit: http://mercor.com/sourcery • VCX—VCX is the public ticker for private tech, allowing investors of all sizes to invest in venture capital. View The Portfolio at http://GetVCX.com • Deel—Deel is the global people platform that helps startups hire, manage, pay, and equip anyone, anywhere. Trusted by more than 35,000 fast-growing companies, Deel is the people platform that just works, so teams can scale without the chaos. Visit: https://www.deel.com/sourcery • Public–Investing platform Public just launched Ge