React Native Developer

As Senior React Native Engineer you are the Mobile tracklead. 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
Identifythe riskiest screens and flows; proposestabilizationplans
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
Kogo poszukujemy?

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)
TanStackQuery / 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)

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