Infrastructure Engineer

Arena

Senior Infrastructure Engineer defining and building technical foundations for AI evaluation platform at Arena Intelligence. Collaborating cross-functionally to ensure performance, reliability, and security at scale.

Posted 4/12/2026full-timeBay Area • California • 🇺🇸 United StatesSeniorLeadWebsite

Tech Stack

Tools & technologies

Distributed Systems

About the role

Key responsibilities & impact

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.

Requirements

What you’ll need

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.

Benefits

Comp & perks

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.

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills & Tools

backend engineeringinfrastructure engineeringsystems engineeringdistributed systemsperformance profilingobservabilityreliability engineeringnetworking fundamentalsservice-to-service communicationtraffic routing

Soft Skills

clear communicationleadershipcollaborationmentoringbuilding alignmentprioritization