Senior Infrastructure Engineer

LMArena

54d

About The Position

LMArena is seeking a Senior Infrastructure Engineer to define, build, and evolve the technical foundations that power the world’s most transparent AI evaluation platform. This is not just an architecture role - you’ll partner directly with product, security, and data teams to identify bottlenecks, design resilient systems, and ship the code that keeps our platform fast, reliable, and secure at scale.
You’ll have a broad impact across the stack: optimizing performance, building primitives that accelerate feature delivery, hardening our systems against abuse, and scaling infrastructure to handle billions of API requests and real-time votes. If you love working across boundaries, getting deep into code, and making infrastructure a product in its own right, this is the role for you.

Requirements

• 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 Haves

• 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.

Responsibilities

• 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.

Benefits

• Comprehensive health and wellness benefits, including medical, dental, vision, and additional support programs.
• The opportunity to work on cutting-edge AI with a small, mission-driven team
• A culture that values transparency, trust, and community impact

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level
• Education Level: No Education Listed
• Number of Employees: 11-50 employees