Senior Mobile Engineer (Flutter + iOS)

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.
 

Company Overview
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.

About This Role

The Senior Software Engineer, iOS is part of the Engineering team and reports to our Manager, Engineering. As Senior Software Engineer, iOS, you will be responsible for designing and building high-quality, scalable iOS applications that deliver secure and seamless user experiences. You will partner with Product, Design, Backend, and QA teams to develop features that meet performance, reliability, and usability standards while contributing to mobile engineering best practices.

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; 5–8+ years of professional mobile development experience, with 4+ years of native iOS in Swift and 1–2+ years of hands-on Flutter/Dart (or strong cross-platform learning track record), including production apps shipped through multiple iOS release cycles.
• Strong proficiency in Swift, UIKit, and/or SwiftUI, with solid command of iOS architecture patterns (MVC, MVVM, VIPER, Clean Architecture) and modern concurrency (Combine, async/await).
• Working knowledge of Dart and the Flutter framework, including at least one state management solution (Provider, Riverpod, Bloc, or GetX) and native ↔ Flutter integration via platform channels / pigeon.
• Strong architectural judgment in platform migrations or codebase rewrites — proven ability to keep a production app stable while progressively migrating features to a new stack (hybrid native + Flutter screens, feature flagging, gradual rollouts).
• Hands-on experience integrating with RESTful APIs, handling asynchronous data flows, and managing app state efficiently across both native and cross-platform layers.
• Proficiency with mobile performance optimization and debugging tools — Xcode Instruments, Flutter DevTools, and Firebase (Crashlytics, Performance Monitoring, Analytics).
• Strong testing fundamentals across iOS and Flutter — XCTest/XCUITest, flutter_test/integration_test, mocking, and CI-integrated automated test suites; familiarity with mobile security best practices (Keychain / Secure Storage, biometric auth, certificate pinning, secure authentication flows).
• Hands-on experience with Git, mobile CI/CD pipelines (Fastlane, Bitrise, GitHub Actions, or Codemagic), and App Store deployment processes (provisioning, TestFlight, App Store Connect, phased rollouts).
• 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); 
• English at B2 / Upper-Intermediate or higher, sufficient for a final technical interview directly with the US client team.

Bonus: 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.