Sr. React Native Engineer

This role is suitable for a Senior React Native Engineer with proven experience shipping and maintaining production apps on both the Apple App Store and Google Play. Required skills include advanced TypeScript, React Native Reanimated, Gesture Handler, GraphQL, TanStack Query, Skia, mobile performance profiling, native modules, Expo/EAS, fastlane, Sentry, and OTA updates. The ideal candidate should be familiar with building gesture-driven animations, optimizing UI and JavaScript thread performance, handling offline and reconnection states, integrating native functionality, and managing complete dual-platform release workflows.

How would you architect a high-performance React Native unboxing animation using Reanimated and Gesture Handler?

I would keep gesture calculations and animation worklets on the UI thread using shared values, minimizing JavaScript thread involvement. Gesture Handler would manage touch input, while Reanimated coordinates transitions, interpolation, and physics-based effects without triggering unnecessary React renders.

How would you diagnose and fix dropped frames in a React Native application?

I would profile the app on real devices using React Native DevTools, Xcode Instruments, and Android Studio Profiler to identify UI-thread, JS-thread, GPU, or memory bottlenecks. Typical fixes include reducing component re-renders, moving work into UI-thread worklets, simplifying view hierarchies, optimizing images, and removing expensive synchronous operations.

When would you use React Native Skia instead of standard React Native views or animations?

Skia is useful for highly custom, GPU-rendered visuals such as card effects, particle systems, shaders, and complex canvas-based transitions. It can reduce the overhead of deeply nested native views while providing precise control over rendering and animation performance.

How would you implement resilient GraphQL data fetching with TanStack Query for live unboxing flows?

I would define stable query keys, configure appropriate stale and cache times, and use mutations with optimistic updates and rollback handlers. Pagination, retry policies, focus and network reconnect behavior, and reconciliation after reconnecting would ensure the UI remains consistent during unstable connections.

How would you handle race conditions between optimistic mutations and server responses?

I would cancel or snapshot affected queries before applying an optimistic update, then reconcile the cache using the authoritative server response. Failed mutations would restore the snapshot, while mutation identifiers or timestamps could prevent stale responses from overwriting newer state.

What is the React Native New Architecture, and how can it improve this application?

The New Architecture uses Fabric for rendering and TurboModules for more efficient native module access, reducing legacy bridge overhead. It can improve responsiveness and startup behavior, especially when custom native functionality or frequent JavaScript-to-native communication is required.

How would you decide whether functionality should be implemented in JavaScript or as a native module?

I would keep product logic and non-critical UI behavior in TypeScript, but move latency-sensitive or platform-specific work to native code. Examples include advanced haptics, high-frequency sensor processing, custom rendering, and operations where bridge or JavaScript scheduling overhead affects frame rate.

How would you manage iOS and Android release pipelines with Expo EAS and fastlane?

I would create reproducible environment-specific build profiles, manage signing credentials securely, and automate versioning, testing, and submission steps. EAS can handle cloud builds and OTA-compatible releases, while fastlane can automate TestFlight, App Store Connect, Google Play tracks, metadata, and distribution tasks.

What precautions would you take when using OTA updates in a production React Native app?

OTA updates should only be used for compatible JavaScript and asset changes, never for changes requiring new native binaries. I would use runtime-version checks, staged rollouts, monitoring, rollback capability, and Sentry validation to prevent an incompatible update from breaking released applications.

How would you investigate a memory leak or crash occurring only on certain Android devices?

I would compare Sentry stack traces, device and OS distributions, memory profiles, and reproduction conditions across affected hardware. I would inspect retained component references, image and animation allocations, native module lifecycles, and list rendering, then verify the fix on budget and high-end devices through profiling and staged release testing.

Pack.com is a stealth, gamified shopping platform backed by an established iGaming and CS2 operator, bringing mystery-pack and loot-box experiences to physical products. As a Senior React Native Engineer, you’ll build and optimize iOS and Android apps with tactile animations, gesture-driven unboxing flows, resilient GraphQL data pipelines, and dual-store release operations. The stack includes TypeScript, React Native, Reanimated, Gesture Handler, Skia, TanStack Query, Expo EAS, Fastlane, Sentry, and native modules; the role is 100% remote across the UK and Poland, with a competitive salary that is not disclosed. It’s worth applying for the opportunity to own a high-impact mobile product, work as a hands-on IC in a lean team, and shape a new app from development through App Store and Google Play launch.