LMArena is hiring a Senior Infrastructure Engineer to define, build, and evolve the technical foundations that power our transparent AI evaluation platform. You will have broad impact across the stack, optimizing performance, building primitives, hardening systems, and scaling infrastructure to handle billions of API requests and real-time votes.
What You'll Do
- Own technical strategy for LMArena’s core infrastructure—networking, APIs, services, data systems, and security foundations.
- Design and implement high-performance systems that scale to hundreds of millions of real-time interactions and evaluations per day.
- Collaborate with security engineering to embed anti-abuse measures, Sybil resistance, and trust systems into core platform architecture.
- Partner with product engineering to deliver infrastructure improvements that directly accelerate feature velocity and reliability.
- Build developer-facing primitives and tooling—internal APIs, SDKs, CI/CD enhancements—that make our platform more productive and safe to build on.
- Monitor, profile, and optimize system performance across backend services, databases, and networking layers.
- Drive operational excellence through observability, capacity planning, and incident response best practices.
- Mentor engineers across the company in building scalable, performant, and secure systems.
What We're Looking For
- 8+ years of experience in backend, infrastructure, or systems engineering, including staff-level scope in a high-scale production environment.
- Proven experience designing and operating distributed systems at scale (millions of DAU / billions of requests).
- Deep knowledge of networking fundamentals, service-to-service communication, and traffic routing at scale.
- Hands-on experience with performance profiling, observability, and reliability engineering.
- Track record of collaborating with security and product engineering to deliver both foundational systems and user-facing features.
- Clear communicator who can lead technical discussions, build alignment across teams, and partner with us to prioritize the needs of the business.
Nice to Have
- Experience with Node.js, Typescript, Serverless Environments, Postgres.
- Background in anti-abuse systems, security engineering, or trust & safety platforms.
- Experience building infrastructure for real-time, user-driven platforms.
Technical Stack
- Node.js
- Typescript
- Serverless Environments
- Postgres
LMArena is an equal opportunity employer.
