Simulation Engineer

ABOUT AARU Aaru operates at the frontier of predictive intelligence, using AI to simulate and predict human behavior at scale. By generating and deploying instances of artificial intelligence that mirror humans, called agents, Aaru simulates entire populations with unprecedented accuracy. Our partners work with us for many reasons: they leverage Aaru to refine strategy in volatile geopolitical climates, cut new product innovation timelines from months to minutes, and deploy marketing campaigns that win in an era where consumers have never been harder to understand. We provide organizations with invaluable foresight, empowering them to anticipate outcomes and proactively make the right decisions at the right time, every time. We're a small, dedicated, mission-driven team and we intend to stay that way. We believe the best work happens when exceptionally talented people are given ownership, trust and the space to operate without bureaucratic friction. We work with urgency and intellectual honesty and expect new team members to match our velocity. We seek individuals who thrive at the frontier, who push beyond conventional limits, who bring curiosity and conviction in equal measure, and who want their work to have demonstrable impact in the world. If you're energized by the idea of a small team doing things that feel impossible, let’s build together. ABOUT THE ROLE As a member of the AI/ML engineering team, you'll directly shape the core simulation systems powering critical predictions for global enterprises. The AI/ML team owns the accuracy and intelligence of Aaru's simulation engine — from synthetic population generation to response estimation. You'll work on designing, training, and evaluating the models that allow us to simulate human behavior with near-perfect fidelity, collaborating closely with research, infrastructure, and product teams. RESPONSIBILITIES Design and implement training environments for language models used in simulation Build focused, high-quality evaluation frameworks for domain-specific prediction tasks Integrate classical ML approaches with deep learning architectures to improve simulation accuracy Develop and iterate on the core modules that power population-level predictions Create and train new models — and finetune existing ones — for accurate simulation of human decision-making across question types Collect, process, and leverage diverse data sources to improve the accuracy of synthetic populations YOU MAY BE A FIT IF You have deep expertise in ML and AI, with meaningful prior work using Large Language Models in production systems You've designed and run rigorous ML experiments, moving from hypothesis to evaluation to deployment You have 3+ years of hands-on experience building ML/AI systems (research or applied) You're comfortable working across the full model lifecycle: data collection, training, evaluation, and production integration You have experience working cross-functionally with engineering and product teams to ship ML-powered features You're deeply curious and motivated to push the boundaries of what simulation technology can do STRONG CANDIDATES MAY ALSO Have publications at top ML venues (NeurIPS, ICML, ICLR, ACL) Have experience building or fine-tuning multi-agent systems Have worked on probabilistic modeling, Bayesian inference, or causal reasoning Have familiarity with our stack or demonstrate the ability to learn unfamiliar technologies quickly LOCATION This role is based in New York City. Aaru is an in-person company, working 5 days a week in office. Candidates are expected to be located within the New York City metropolitan area or open to relocation. BENEFITS At Aaru, we take care of our people. In addition to a competitive base salary and equity participation, we offer comprehensive medical, vision, and dental coverage, visa sponsorship and relocation support, and various other benefits and perks.