React Native Developer

As Senior React Native Engineer you are the Mobile track lead. You partner with our Senior Android/Kotlin engineer (responsible for the native bridge), set the standard for the mobile codebase, lead audits and the knowledge-transfer sessions from the client's mobile team, and ship features once we take ownership.

This is a player-coach role: ~70% hands-on, ~30% leadership (architecture, code review, hiring panels). 

First 90 days

• Read and document the mobile codebase alongside the outgoing engineering team
• Produce a quality baseline: TypeScript strictness compliance, test coverage, dependency freshness, app size, cold-start time, frame-rate profile
• Audit the JSI / Nitro Module bridges — especially the bridge into the Kotlin fitness-equipment SDK
• Identify the riskiest screens and flows; propose stabilization plans
• Lead knowledge-transfer sessions for the mobile app

Ongoing

• Own architecture decisions for the mobile app
• Lead design reviews for new screens and flows
• Pair with mid-level mobile engineers
• Manage app-store release pipelines
• Participate in on-call rotation for mobile-side crashes

Must-have skills

• 5+ years mobile development, of which 3+ years React Native in production
• React Native bridgeless mode + Hermes — production experience, not just exposure
• JSI / Nitro Modules — built or maintained at least one native module bridge in production. Nitro Modules specifically is rare — JSI native-module experience is acceptable; pure Nitro is a bonus.
• TypeScript strict mode — generics, narrowing, no any-as-escape
• State management with Zustand (or comparable: Redux Toolkit, Jotai)
• TanStack Query / React Query at production scale
• Reanimated 4 + gesture-handler — building actual animated UIs
• Auth0 mobile SDK or comparable OIDC mobile flow
• iOS native integration — Xcode comfort, Swift/Objective-C reading, CocoaPods, app provisioning, TestFlight
• Android native integration — Android Studio comfort, Gradle, Kotlin reading
• App-store deploy pipelines — Fastlane, Bitrise, or EAS Build
• Crash analytics — Firebase Crashlytics or comparable
• Working English

Nice-to-haves

• Skia / GPU rendering in RN
• NativeWind or Tailwind-for-RN
• Bluetooth Low Energy (BLE) integration in RN
• HealthKit / Health Connect integration
• Experience working with a multi-platform native SDK
• Performance profiling with Flipper or RN Performance Monitor
• E2E testing on mobile (Detox, Maestro)