Founding Product Security Engineer

ABOUT ARENA INTELLIGENCE Arena is the platform for evaluating how AI models perform in the real world. Founded by researchers from UC Berkeley's SkyLab, we're on a mission to measure and advance the frontier of AI for real-world use, and to build the foundation for everyone to understand, shape, and benefit from it. Tens of millions of people use Arena each month to evaluate how frontier systems handle the work they actually do. The preferences they share power the most transparent, rigorous, and human-centered evaluations in AI. Leading AI labs, enterprises, and independent researchers rely on our work and open datasets to understand how models behave in real workflows: agentic coding, creative generation, professional productivity, and beyond. We go beyond leaderboards and decompose what human experience reveals about AI, so models advance toward the work people actually do. We're a team of researchers, academics, builders, and creatives from UC Berkeley, Google, Stanford, and DeepMind. We seek truth, move fast, and value craftsmanship, curiosity, and impact over hierarchy. We're building a company where thoughtful, curious people from all backgrounds can do their best work together, in an office culture that radiates excellence, energy, and focus. ABOUT THE ROLE Arena Intelligence is seeking a Founding Product Security Engineer to lead the strategy, design, and hands-on implementation of the systems that protect Arena from attackers and keep our platform trustworthy as we scale. You'll work across product, infrastructure, and data pipelines to proactively identify risks, embed security into core features, and build the platform primitives — identity, session, behavioral signals, secure APIs, model-inference-path controls — that every other team at Arena builds on top of. This is a builder role. You will not only set technical direction but also write the code, build the tools, and design the frameworks that make security part of our product's DNA. Your work will