---
title: 'Backend Engineer at Arena Intelligence, Inc.'
canonical: 'https://feeny.ai/job/backend-engineer-arena-intelligence-inc-bay-area-w7ezg3qh0b1h'
type: 'job'
last_seen: '2026-09-11'
---

# Backend Engineer at Arena Intelligence, Inc.

- **Company:** Arena Intelligence, Inc.
- **Location:** Bay Area
- **Employment:** full-time
- **Work type:** hybrid
- **Posted:** 2026-07-16
- **Last confirmed live:** 2026-09-11
- **Apply:** https://jobs.ashbyhq.com/arena/7490c92c-e7a0-4629-b9b8-eb89d5862527

## 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 backend engineer to build the products and platforms that sit on top of our evaluation systems - the APIs, services, and data systems that turn Arena’s evals into products that enterprises depend on.

This is the application layer of the Arena Service. Where our infrastructure teams builds the gateways and runtimes beneath - you will work closely with them to build the backends that customers will touch directly. This will include the APIs that expose Arena and enterprise data and the systems that manage usage, billing and multi tenant access. This work spans product surfaces of varying maturity and the data pipelines behind them - zero to one in places and scale-it up in others. You'll be an early member of our enterprise team, working closely with infrastructure engineers, researchers, and product leadership. We move fast and stay rigorous.

## What You'll Do

- Build API-based products from the ground up. Design and ship the low-latency, high-reliability APIs and services that power Leaderboards, Evals, and Arena data products — clean, versioned, and built for the developers who consume them.
- Turn evaluations into product. Partner with the research team to take novel eval methods and make them durable, full-featured products: scoring pipelines, data models, and the APIs that expose them.
- Ship enterprise-grade backends. Usage metering, cost attribution, billing integration, authentication, RBAC, multi-tenancy, and audit logging — the systems enterprise customers expect.
- Own the data architecture. Unify our public and private evaluation data, design schemas that hold up as the product grows, and make Arena’s data queryable, consistent, and fast.
- Flex across the stack. Contribute to the backend of our Leaderboards and Evals platforms when needed, helping unify our public and private data architectures.

## What We're Looking For

- 5+ years of backend engineering experience, with meaningful time spent on building product facing APIs, services and data systems at scale
- Strong proficiency in a modern backend language — Go preferred — and the judgment to design APIs other engineers and customers will live with for years.
- Solid data fundamentals. You’re comfortable modeling, querying, and scaling Postgres, and you know when to reach for Redis, a queue, or a warehouse.
- Experience composing services into products — integrating payments, auth, analytics, or data pipelines into something coherent and reliable.
- A product-oriented mindset. You think about the developer experience of your APIs, not just the implementation. You ask “why” before “how.”
- Comfort with ambiguity. We’re a startup. Scope is fluid, context shifts, and you’ll wear many hats. That should sound exciting, not stressful.

## Nice to Have

- Experience with LLM provider APIs (OpenAI, Anthropic, Google, etc.) and the realities of building on them: streaming, token accounting, rate limits, model-specific quirks.
- Background in ML infrastructure, model serving, or evaluation frameworks.
- Experience building enterprise-ready features: SSO, RBAC, audit logs, multi-tenancy.
- Experience building billing and usage infrastructure around systems like Stripe, Metronome, and Orb.
- Familiarity with the modern AI stack (vLLM, LiteLLM, LangChain, etc.).

## What we offer

- We offer competitive compensation and equity aligned to the markets where our team members are based. The base salary range will depend on the candidate’s permanent work location.
- 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

Come help build the space where anyone can explore and help shape the future of AI.

Arena Intelligence provides equal employment opportunities (EEO) to all employees and applicants for employment without regard to race, color, religion, sex, national origin, age, disability, genetics, sexual orientation, gender identity, or gender expression. We are committed to a diverse and inclusive workforce and welcome people from all backgrounds, experiences, perspectives, and abilities.

## About Arena Intelligence, Inc.

## Company Overview
- **One-liner**: Arena Intelligence, Inc. (formerly LMArena/Chatbot Arena) operates a public, community-driven platform for evaluating large language models through anonymous head-to-head comparisons and voting.
- **Entity Type**: Private (Series A, total $250M funding)
- **Headquarters**: San Francisco, California, United States
- **Founded**: 2025 (company incorporation; platform launched April 2023)
- **Founders**: Wei-Lin Chiang, Anastasios N. Angelopoulos, Ion Stoica

## Core Business
- **Primary industry**: AI evaluation and research infrastructure
- **Target customers**: AI labs (OpenAI, Google DeepMind, Anthropic, DeepSeek), enterprises, researchers, and the general AI community (B2B and B2C)
- **Mission**: Fuel the world’s most trusted AI evaluation platform, using real-world community votes to benchmark model performance

## Products & Services
- **LMArena Platform**: Public web-based platform where users enter prompts for two anonymous models, vote on the better response, and then see the models’ identities. Supports text, vision, web dev, search, video, and image modalities. Over 50 million votes collected.
- **Max (Model Router)**: An intelligent orchestrator that routes each user prompt to the most capable model for that specific prompt, powered by 5+ million real-world votes.
- **Enterprise Evaluation Product**: Launched September 2025, provides rigorous, reproducible evaluations for AI labs and enterprises, generating actionable feedback on model performance.

## Market Standing
- **Valuation/Market Cap**: Not publicly disclosed
- **Key Metric**: $100M annualized revenue run rate as of June 2026 (achieved within 8 months of enterprise offering launch)
- **Total Funding**: $250M (Seed $100M led by Andreessen Horowitz and UC Investments in June 2025; Series A $150M led by Felicis and UC Investments in January 2026)
- **Notable Investors/Partners**: Felicis, UC Investments, Andreessen Horowitz, The House Fund, LDVP, Kleiner Perkins, Lightspeed Venture Partners, Laude Ventures
- **Growth Signals**: Community grew 25x in one year; 50 million votes, 400+ model evaluations, 145k open-source battle data points; operates in 5 countries (US, Germany, UK, UAE, Canada); headcount of 49 with +10.5% monthly growth

## Competitive Advantages
- **Community-driven data**: Trusted by major AI labs for real-world, reproducible evaluations; 10M+ community members contribute diverse prompts and votes
- **First-mover & brand**: The de facto public leaderboard for LLM comparison; used for pre-release model testing (e.g., DeepSeek R1, GPT-5 "summit", Gemini 2.5 Flash Image "Nano Banana")
- **Open science**: Academic partnerships program funding independent research on AI evaluation methodology
- **Revenue velocity**: Achieved $100M ARR in under a year from enterprise launch, indicating strong product-market fit

## Strategic Focus
- Scale the platform with new features and modalities (video, search, web dev)
- Deepen enterprise offerings and model routing capabilities (Max)
- Expand academic partnerships to advance the science of AI evaluation
- Continue to serve as the gold standard for real-world model performance benchmarking

## Why Work Here
- **Culture**: Fast-moving, research-driven startup with roots at UC Berkeley; emphasis on community, open source, and rigorous science
- **Team**: 49 employees, 41% technical (Data Engineers, ML Scientists, ML Engineers, Software Engineers), with talent from top AI labs and universities (Berkeley RISE Lab, Google, Apple)
- **Growth**: High-growth environment (revenue run rate doubled rapidly, headcount growing ~10% monthly)
- **Location**: Headquarters in San Francisco (2261 Market St., Ste 85064); offices also in SF (two additional locations). Likely hybrid/office-based given SF HQ and local employee concentration.
- **Perks**: Not explicitly listed, but typical for VC-backed startup (equity, competitive comp, impact on foundational AI infrastructure)

## Sources
1. [arena.ai](https://arena.ai/)
2. [arena.ai/blog/series-a](https://arena.ai/blog/series-a/)
3. [linkedin.com/company/arenaai](https://www.linkedin.com/company/arenaai)
4. [jobs.ashbyhq.com/arena](https://jobs.ashbyhq.com/arena)

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