Senior Frontend Engineer, Prediction Markets (React Native)

CultureMill Recruiting; San Francisco (CA); Hybrid; USD 150,000 - 210,000; Full time

Job summary

CultureMill Recruiting is seeking a mobile-focused developer for a prediction markets role. You’ll work on a React Native/TypeScript stack, building surfaces where users browse markets, compose entries, and track live positions, with real-time streaming behind the scenes.

The role requires deep RN expertise, performance profiling, and experience with live data systems. It is a hybrid position based in the Bay Area, collaborating with designers and backend engineers on streaming contracts.

Qualifications

• 4+ years building mobile apps with React Native as the primary craft.
• Deep React Native experience with performance profiling and native boundary knowledge.
• Strong TypeScript and fluency in the modern RN ecosystem.
• Experience with real-time or high-correctness surfaces and live data streams.
• Experience delivering consumer-scale products within mature codebases.
• Ability to own and communicate technical decisions, and work hybrid from San Mateo.

Responsibilities

• Build and own prediction market surfaces for browsing, entry composition, live positions, and results.
• Extend the real-time layer with streaming updates and cached state for accuracy as prices move.
• Own performance on dense surfaces with frequent updates and smooth animations.
• Collaborate with design and backend engineers on product and streaming contracts.

Skills

React Native

TypeScript

WebSockets

Real-time data

Performance profiling

Mobile development

Tools

React Native tools

Native boundary

Job description

Our client is a mobile sports platform where tens of millions of fans play and compete — a decade-old fantasy business now moving fast into real‑money games: daily fantasy sports and prediction markets. They're backed by several of the most respected venture firms in Silicon Valley, and the team is small, senior, and flat, where engineers own real surface area.

Role Overview

This role sits on prediction markets — launched earlier this year, and being built out now.

Markets move while a user is watching them and composing an entry, with real money riding on what's on screen. A stale price or a dropped update isn't a cosmetic bug — it's a trust problem. And it has to hold up on a phone, during live-sports traffic spikes.

The platform is React Native with TypeScript, react-query, react-navigation, and reanimated — a mature codebase serving millions, not a greenfield project. This is a mobile role, not web.

What You'll Do

• Build and own prediction market surfaces — where users browse markets, compose an entry, track live positions, and see results land.
• Extend the real‑time layer behind them: streaming market updates reconciled against cached client state, so what's on screen stays accurate as prices move.
• Own performance on dense, high‑frequency surfaces — frequent updates, long lists, real animation, no dropped frames.
• Work directly with design and backend engineers on the product and streaming contracts behind these screens.

Who You Are

• 4+ years building mobile, with React Native as your primary craft — not a web engineer who has shipped a React Native screen.
• Real depth in React Native. You've profiled and fixed performance problems, worked at the native boundary, and can explain why something was slow rather than just what you tried.
• Strong TypeScript and real fluency with the modern RN ecosystem.
• Experience with real‑time or high‑correctness surfaces — websockets and live data, or products where being wrong costs money: trading, payments, checkout, ticketing.
• Consumer products at meaningful scale, inside mature codebases — not exclusively 0→1 projects.
• You can go deep on your own work — what you personally decided, and what you’d do differently.
• Bay Area based, able to work hybrid from their San Mateo office.
• Bonus: you're a sports fan who actually plays.