Software Engineer - Platform

Arena; San Francisco (CA); On-site; USD 140,000 - 230,000; Full time

Job summary

Arena Intelligence is seeking a Software Engineer - Platform to build the core infrastructure beneath our online evaluation systems—the AI gateways, automated arena runtimes, and the serving layers that enable real-world model evaluation at scale.

You will join an early infrastructure team, work closely with researchers and engineers, and help ensure the system remains scalable, reliable, and fair under heavy load as we expand enterprise usage.

Responsibilities

• Build core infrastructure for online evaluation systems, including AI gateways and runtimes.
• Ensure scalable, reliable infrastructure to handle bursty traffic and diverse models.
• Collaborate with researchers and engineers to ship infra features.

Job description

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 looking for a Software Engineer - Platform to build the core infrastructure that sits beneath our online evaluation systems — the AI gateways, automated arena runtimes, and serving layers that make real-world model evaluation possible at scale.

This is a critical part of the Arena Service. Arenas are live, online systems: they route traffic across frontier models from many providers, handle bursty and unpredictable load, need to fail gracefully when upstream models do, and have to remain fair and consistent under all of it. We exist to build foundational infrastructure for our users that scales, is reliable, and makes the complexities of operating this infrastructure at scale disappear. We need a practitioner who's shipped this kind of infrastructure before and knows where the sharp edges are.

Our AI gateway is currently in private, gated launch with individual developers as our primary users today; enterprise use cases will follow later. Next month we're shipping direct model access and new infrastructure features, and Arena may begin collecting usage traces and building leaderboards shared with lab partners — so there's a lot of near-term, zero-to-one work ahead.

You’ll be an early member of our infrastructure team, working closely with researchers, engineers,