Senior Mobile Engineer – React Native Performance

Root; Los Angeles (CA); Hybrid; USD 140,000 - 180,000; Full time

Job summary

Root is hiring a Senior Mobile Engineer to elevate the performance, reliability, and technical quality of Root’s React Native client on Android and iOS. You will optimize long message feeds, real-time updates, and media-heavy communities, striving for fast startups and smooth rendering across devices.

In this high-autonomy role you will profile production apps, own substantial areas of the mobile codebase, and drive architectural decisions.

Qualifications

• 5+ years of professional mobile development experience, including 3+ years building and shipping React Native applications to production.
• Demonstrated experience diagnosing and fixing real performance issues in React Native with measurable results.
• Deep understanding of React rendering behavior, hooks, memoization, virtualized lists, and render optimization at scale.
• Strong TypeScript experience in large, production React Native codebases.
• Experience building real-time or communication-oriented mobile applications.
• Strong understanding of Android and iOS platform differences and how they impact React Native performance and UX.
• Ability to independently own and drive complex features or refactors end-to-end.
• Track record of improving codebase quality through patterns, conventions, or mentorship.
• Experience with Expo SDK and EAS build/update workflows.
• Familiarity working in a monorepo environment.
• Experience with gRPC or strongly typed API contracts in mobile clients.
• Experience optimizing apps for mid-range or low-end Android devices.
• Experience writing or debugging native modules when JS-side optimization is insufficient.
• Public writing, talks, or open-source contributions related to React Native performance.

Responsibilities

• Lead Mobile Performance Optimization.
• Profile and eliminate performance bottlenecks in React Native rendering, navigation, and state management.
• Optimize long list rendering for high-volume message feeds and community views.
• Reduce startup time, memory footprint, and JS thread blocking.
• Improve real-time update performance (messaging, presence, WebRTC).
• Establish measurable baselines and improve across devices.
• Co-Own significant Android and iOS client areas end-to-end.
• Contribute to mobile architecture decisions and patterns.
• Raise the bar in code reviews focusing on performance, correctness, maintainability.
• Partner with backend on API and real-time integration details.
• Build and ship features required for monetization parity.
• Implement community management and moderation tooling.
• Integrate internal app platform into the mobile client.
• Work in Turborepo monorepo with shared logic and generated gRPC clients.
• Build with Expo SDK, Expo Router, Redux Toolkit, RTK Query.
• Manage builds/releases through EAS across environments.
• Create and maintain strict TypeScript throughout the codebase.

Skills

React Native performance optimization

TypeScript

Performance profiling

Monorepo experience

Expo SDK / EAS build

Tools

Hermes

Flipper

React DevTools

Native profilers

Expo SDK

EAS build

Redux Toolkit

RTK Query

gRPC

Job description

Root is hiring a Senior Mobile Engineer to elevate the performance, reliability, and technical quality of Root’s React Native client on Android and iOS. You will optimize long message feeds, real-time updates, and media-heavy communities, striving for fast startups and smooth rendering across devices.

In this high-autonomy role you will profile production apps, own substantial areas of the mobile codebase, and drive architectural decisions.