Senior React Native Engineer (Latam & North America)

About the Role

This is a contractor role through X-Team. You'll own the mobile architecture behind a real-time trading experience — the kind of app where a dropped frame during a fast market means a trader misses a price. Every screen you touch, from a candlestick chart re-rendering thousands of points a second to an options chain repainting under high-frequency updates, has to hold its frame budget while real market data pushes against it.

The legacy bridge is gone. This isn't a New Architecture migration project — it's about going deep on JSI, Fabric, Turbo. Modules, and bridgeless mode, and setting the standards every other engineer on the team builds against. Most important: Open to candidates based in North America or Latam 8+ years building production mobile applications, including 5+ years in React Native at senior level or above Demonstrable architect-level ownership — you've designed a mobile architecture that other engineers built on for years, not just delivered features inside one Deep, hands-on experience with React Native's New Architecture: JSI, Fabric, Turbo.

Modules, Codegen, and bridgeless mode, including custom native modules and components you wrote yourself Strong native iOS and Android skills: Swift/Objective-C++ and Kotlin, with real comfort in C++ for shared cores or performance-critical paths Proven multithreading work in React Native: worklets, worklet runtimes, Reanimated internals, background runtimes, and the serialization/lifetime rules that make them safe A track record of sustained 60–120fps under real-time data load, with concrete before/after numbers you can walk through Real-time data experience: high-message-rate Web.

Socket streaming, backpressure handling, binary protocols, and architectures that decouple ingest rate from render rate High-performance charting experience in React Native — Skia, GPU canvas, or a custom native renderer — beyond dropping in an off-the-shelf chart library Expert-level profiling across Hermes, Perfetto/Systrace, Instruments, React Dev.

Tools, and Flashlight The bonus skills: Experience at a trading, brokerage, crypto exchange, or high-frequency fintech app, or comparable real-time consumer scale elsewhere Options-specific product work: options chains, multi-leg order tickets, greeks, payoff diagrams, implied volatility surfaces Nitro Modules, or other experience reducing JS↔native call overhead on hot paths Open source contributions to the React Native ecosystem, or conference/blog work on RN performance Experience in a regulated environment: security review, certificate pinning, tamper/jailbreak detection, auditability, accessibility compliance Experience running OTA/Code.

Push-style release infrastructure with feature-flagged rollouts Personal traits: Measures before touching code — diagnoses whether a stall is JS thread, UI thread, commit phase, GC, or GPU before reaching for a fix Comfortable being the final call on hard architectural trade-offs, like deciding when a screen needs a native fallback and owning both sides of it Writes the design docs and runs the architecture reviews, not just the code — raises the bar for everyone around them Treats a dropped frame as a bug, not a nice-to-have Mentors naturally, pairing on the hard traces and sharing what the profiler actually revealed