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React Native Engineer

SumCircle Technologies Private Limited

2 - 5 years

Bengaluru

Posted: 01/01/2026

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Job Description

Senior React Native Engineer Mobile Trading & Realtime Systems

Location: Banglore

Team: Mobile

Type: Full-time


  • Mission

Own our mission-critical mobile apps built with React Native (TypeScript) and Expo. Youll deliver a fast, reliable, and secure trading experience with realtime data, offline resilience, and zero-downtime updates via Expo EAS.


  • What Youll Do
  • Build high-performance RN apps with TypeScript, React Navigation, and modern state management (Zustand/Jotai/Redux Toolkit).
  • Own Expo/EAS workflows: managed/bare transitions, EAS Build, EAS Submit, EAS Update (OTA) channels/rollbacks, runtime versioning, and multi-env release strategies.
  • Realtime UX: Integrate websockets/Server-Sent Events for live markets; design efficient list virtualization, windowing, and incremental rendering to keep P95/P99 frames smooth.
  • Performance & stability: profile with Flipper/Hermes profiling/Systrace, optimize bridge usage, and adopt TurboModules/JSI where needed.
  • Native integrations: design and maintain light native modules (Kotlin/Swift/Obj-C) for critical paths (secure storage, biometrics, low-latency sockets).
  • Quality & security: ship with full test coverage (unit, component, contract, E2E with Detox/Maestro), robust error handling, code-push guardrails, secure secrets handling.
  • Observability: instrument mobile telemetry (crashlytics/Sentry, OpenTelemetry), build dashboards, and drive data-informed iteration.
  • Release engineering: implement canary rings, phased rollouts, forced updates, feature flags/experiments, and app store compliance checks.
  • Collaboration: partner with Backend/Infra to shape APIs, caching, pagination, and backpressure strategies; contribute to design reviews and RFCs


  • Minimum Qualifications
  • 5+ years building production mobile apps, 3+ years with React Native (TypeScript).
  • Deep experience with Expo + EAS (Build, Submit, Update/OTA, runtime versioning, update groups, rollbacks).
  • Strong command of mobile performance: render lifecycles, React concurrency, memoization strategies, list virtualization, image caching, and animation optimization (Reanimated).
  • Solid understanding of networking & realtime on mobile (websocket lifecycle, reconnect/backoff, QoS, regional endpoints, metered networks).
  • Proficient with secure storage & auth (biometrics, device binding, keychain/keystore, OAuth/OIDC/PKCE, session management, jailbreak/root detection signals).
  • Testing discipline: Jest + RTL, contract tests against mock servers, E2E (Detox/Maestro) in CI, flake-resistant test design.
  • CI/CD for mobile: Fastlane or EAS pipelines, signing management, env-driven configs, artifact provenance, and store submission automation.
  • Experience shipping on iOS and Android; comfort with Xcode/Gradle, provisioning, and store review nuances
  • Bonus Points
  • JSI/TurboModules, Fabric, custom native views, and bridging performance-critical paths. Offline-first architectures (normalized caches, optimistic updates, background sync).
  • Data visualisation on mobile (high-frequency charts with downsampling/decimation).
  • Accessibility (WCAG), internationalization, RTL, and dynamic type.
  • App telemetry privacy models, consent flows, and regional compliance.
  • Background tasks, push notifications, deep links, universal links, and widgets.
  • Experience in trading/fintech, high-reliability or safety-critical apps.

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