Simile

Simile builds AI models that simulate how people make decisions. Its customers use simulated users for work such as marketing and product research: the model takes data about individuals and simulates how they might respond to a new product, a feature change or another business decision before the company commits real budget. Simile describes the result as a foundation model for human behavior rather than a general-purpose language model, trained to represent differences in people's preferences, experiences, values and decision patterns.^[1],[2],[3]

On its own site the company frames the product as simulation rather than prediction. Each Simile population starts with real people; the company says it designs large-scale studies daily and combines that data with proprietary human-behavior datasets to train its models. It validates against real humans weekly, with more than 7,000 evaluations across subpopulations and enterprise use cases, and tags every result with a predicted accuracy level from an AI confidence model. Customers can also bring their own data, such as loyalty data, balance histories or telemetry, to train a custom model.^[4]

The research behind the company is public. CEO Joon Sung Park was lead author of the 2023 paper Generative Agents: Interactive Simulacra of Human Behavior, which placed 25 AI agents in a simulated town where they formed relationships and routines without every interaction being scripted. Later work from the same group tested whether generative agents built from qualitative interviews could reproduce the attitudes of 1,052 real participants; the agents reached 85% of the consistency the participants themselves showed when re-answering the same questions two weeks apart.^[3]

Simile is a Stanford spinout based in Palo Alto. Tech Funding News reports the company was founded in late 2025 and launched publicly in February 2026, when it emerged from stealth with its Series A. The founding team worked together at Stanford: Park completed his PhD advised by Michael Bernstein and Percy Liang, and the trio had previously built the Smallville simulation that demonstrated AI agents could be used to study the behavior of individuals and groups. SiliconANGLE reported the production model took seven months to develop and was trained on interviews with hundreds of people plus transaction logs and scientific-journal text.^[5],[2]

Growth since launch has been fast by the company's own account. No absolute revenue figure has been disclosed.^[3]

Simile has raised two rounds in 2026. The Series A, announced in February, was a US$100 million round led by Index Ventures, with participation from Hanabi, A*, Bain Capital Ventures and angels including Andrej Karpathy, Fei-Fei Li, Adam D'Angelo, Guillermo Rauch and Scott Belsky. Latham & Watkins represented the company. Index partner Shardul Shah announced the deal in a blog post.^[6],[2]

Five months later, on July 30, 2026, the company said it had closed a $200 million Series B at a $2 billion valuation. Greenoaks led, with participation from Index, Hanabi, Bain Capital Ventures, A*, Factory, Definition and CVS Health Ventures. Index increased its stake; Definition was the only new institutional investor. The company said it would use the money to advance its behavior model, improve simulation reliability and expand into healthcare, financial services, consumer products and media.^[1],[3]

Joon Sung Park is co-founder and CEO. The other co-founders are Michael Bernstein, a Stanford HCI professor, Percy Liang, director of Stanford's Center for Research on Foundation Models, and Lainie Yallen. Park's stated mission for the company is to simulate all eight billion people on earth, accurately and honestly; TechCrunch called that goal preposterous while allowing that simulated users for research is a promising area.^[5],[1]

Early customers disclosed at the Series A were CVS Health and Telstra, Australia's largest mobile internet provider. By the Series B, Tech Funding News listed CVS Health, Wealthfront, Deloitte and Gallup as users. CVS Health Ventures is also an investor. Simile's own site carries testimonials from executives at CVS Health, Wealthfront, Banco Itaú, Suntory Beverages & Food, Gallup and Garnett Station Partners; Wealthfront's head of user research says Simile expanded its qualitative research scope 15X.^[2],[5],[4]