Senior React Native Developer

Sigmasoft is hiring a Senior React Native Developer to help build and maintain consumer mobile experiences on both iOS and Android. This role focuses on owning the React Native codebase end to end, optimizing performance, integrating with native capabilities, and strengthening testing across the mobile layer. The team also expects collaboration around a migration effort from React Native toward native iOS and Android when it makes sense.

Role summary

As a Senior React Native Developer, you will develop consumer features built with React Native, supporting experiences such as CGM data visualization, AI-powered food logging, personalized metabolic insights, and AI health assistant functionality. You will handle implementation details from architecture and design through testing, maintenance, and performance work across a wide range of devices and OS versions.

Responsibilities

• Build and maintain consumer mobile features across iOS and Android using React Native, including CGM data visualization, AI-powered food logging, personalized metabolic insights, and AI health assistant experiences.
• Own areas of the React Native codebase end to end, spanning architecture and design, implementation, testing, and ongoing maintenance.
• Write clean, well-tested, performant React Native code that runs reliably across many iOS and Android devices and OS versions.
• Diagnose and resolve performance issues in the React Native layer, including JavaScript thread bottlenecks, render optimization, and memory management.
• Work with native modules and understand the React Native bridge to iOS and Android platform capabilities, including integrations with CGM hardware SDKs and Bluetooth data streams.
• Participate in Lingo’s ongoing migration from React Native toward native iOS and Android where appropriate, contributing input on what to migrate and how.
• Conduct code reviews that raise quality across the mobile team, emphasizing readability, testability, and maintainability.
• Partner with Product and Design to convert requirements into well-scoped engineering solutions, pushing back constructively when scope or approach adds unnecessary complexity.
• Contribute to mobile testing practices, including unit, integration, and end-to-end testing across the React Native layer.

Requirements

• Bachelor’s degree in computer science, Engineering, or a related technical discipline.
• 5+ years of professional software engineering experience, with at least 3 years using React Native as a primary technology in a production consumer application.
• Strong, demonstrable React Native expertise, including component architecture, state management, navigation, performance optimization, and the React Native new architecture (JSI, Fabric, Turbo Modules).
• Working knowledge of iOS and/or Android platform fundamentals to understand how React Native interacts with native code and to debug effectively when evaluating native module usage.
• Experience using native modules in a React Native application, including consuming existing native modules and understanding how they bridge to platform capabilities.
• Solid understanding of mobile application architecture patterns, including state management solutions (Redux, Zustand, or equivalent), navigation libraries, and offline-first design.
• Experience profiling and optimizing mobile performance at the React Native layer, including diagnosing JavaScript thread and render performance issues.
• Experience writing automated tests for React Native, including unit and integration tests, plus familiarity with end-to-end testing frameworks.

Technologies

• React Native, iOS, Android
• JSI, Fabric, Turbo Modules
• Redux, Zustand
• Swift, Kotlin
• Core ML, TensorFlow Lite

Preferred qualifications

• Hands-on experience writing native iOS code in Swift and/or native Android code in Kotlin, beyond reading and debugging into actively building native modules or platform-specific features.
• Experience in consumer health, digital health, or regulated industries where software quality impacts end users.
• Familiarity with CGM, biosensor, or IoT data integration in mobile apps, especially real-time data streams from wearable hardware.
• Exposure to Bluetooth Low Energy protocols and mobile SDK integration for wearable or connected health devices.
• Exposure to on-device AI or ML capabilities such as Core ML or TensorFlow Lite integrated within a React Native application.
• Experience with app store release processes for iOS and Android, including CI/CD pipeline integration for mobile builds.
• Prior experience at a high-growth consumer technology company or digital health environment.

Location and work setup

• Alameda, CA (3-4 days/week onsite)
• Work location: In person

Compensation

• USD 70 per hour