Senior Mobile Engineer (Flutter + iOS) (#5186)

N-iX is a global software development service company that helps businesses across the globe create next-generation software products. Founded in 2002, we unite 2,400+ tech-savvy professionals across 40+ countries, working on impactful projects for industry leaders and Fortune 500 companies. Our expertise spans cloud, data, AI/ML, embedded software, IoT, and more, driving digital transformation across finance, manufacturing, telecom, healthcare, and other industries. Join N-iX and become part of a team where your ideas make a real impact.

Our client is a leading, fully regulated US-based digital asset trading platform. They provide secure, low-latency access to cryptocurrency markets, acting as a bridge between traditional finance and the Web3 ecosystem.

The Senior Mobile Engineer will play a pivotal role in transitioning the core mobile platform from native environments to a unified Flutter/Dart codebase. You will maintain the stability of the existing production iOS app while architecting and developing robust, scalable cross-platform features, ensuring a seamless migration process.

Key Responsibilities:

• Maintain, enhance, and support our production native iOS application written in Swift.
• Collaborate on the design and development of a new Flutter/Dart codebase, ensuring performance and scalability.
• Own end-to-end delivery of mobile features, including development, testing, release, and ongoing support
• Build clean, modular, and reusable code to support scalable mobile architecture
• Collaborate with Product, Design, and Backend teams to define requirements and deliver high-quality features
• Optimize app performance, responsiveness, and reliability across a range of iOS devices
• Integrate RESTful APIs and ensure efficient data handling and state management
• Participate in code reviews and contribute to maintaining high standards of code quality and maintainability
• Identify and resolve performance bottlenecks, bugs, and technical issues
• Partner with QA and DevOps to support CI/CD pipelines, automated testing, and release processes
• Mentor junior engineers and contribute to a culture of continuous improvement

Required Qualifications:

• Bachelor's degree in Computer Science or a related field;
• 5+ years in mobile development experience: 3+ years of native iOS (Swift) and 2+ years of Flutter/Dart (or strong cross-platform experience with proven learning track).
• Strong expertise in iOS development: Swift, UIKit/SwiftUI, architecture patterns (MVC, MVVM, VIPER, Clean), and modern concurrency (Combine, async/await)
• Hands-on Flutter experience: Dart, state management (Provider, Riverpod, Bloc, or GetX), and native–Flutter integration (platform channels/pigeon).
• Proven experience in app migration or hybrid architectures (native + Flutter), ensuring production stability during transition.
• Solid experience with REST APIs, async data handling, and state management across mobile layers.
• Experience with performance optimization and debugging tools (Xcode Instruments, Flutter DevTools, Firebase).
• Strong testing practices: XCTest/XCUITest, flutter_test/integration_test, CI-integrated automation.
• Familiarity with mobile security best practices (secure storage, biometrics, certificate pinning, auth flows).
• Experience with Git and CI/CD pipelines (Fastlane, Bitrise, GitHub Actions, Codemagic), App Store processes (TestFlight, App Store Connect).
• Experience working in FinTech, banking, trading, or other highly regulated environments, with a strong collaboration and mentorship mindset across cross-functional teams (Product, Design, Backend, QA, Android); 
• Upper-Intermediate level of English or higher.

Preferred Qualifications:

• Exposure to Android (Kotlin) and full cross-platform transitions; mobile analytics/push notifications (APNs, FCM); and crypto / Web3 mobile integrations - wallet flows, WalletConnect, MetaMask SDK, transaction signing, on-chain data display.