Greenoaks led the new round. Index Ventures, Hanabi, Bain Capital Ventures, A*, Factory and CVS Health Ventures all added to their positions, and Definition invested for the first time. Total funding now exceeds $300M in less than six months.
The technology descends from a famous Stanford experiment. CEO Joon Sung Park’s 2023 paper dropped 25 AI agents into a virtual town called Smallville, where they formed friendships and daily routines without any human scripting, winning Best Paper at UIST. Park then co-founded Simile with Stanford professors Michael Bernstein and Percy Liang and Lainie Yallen, launching publicly in February 2026.
Instead of generating content faster, the startup simulates how customers, patients, employees or citizens will react to a decision, then scales the scenario before a company spends real budget. An insurer might test a new benefits plan on simulated patients before a national rollout.
Revenue has multiplied fivefold since launch and headcount is past 50. A confidence model scores each simulation’s reliability, answering the usual criticism that synthetic users are only as calibrated as their training data.
The capital funds model training, simulation compute and commercial teams in healthcare, financial services and media. Park describes the goal as simulating all eight billion people on earth accurately and honestly.
