Yan – Swift, Kotlin, Flutter

A quit-smoking app with 8M+ downloads and 185K five-star ratings.

• Developed and integrated new features in collaboration with the University of East Anglia, including user surveys and an AI chat assistant.
• Maintained and optimized the existing codebase across Android and iOS platforms.
• Led Java-to-Kotlin migration across about 20% of the Android codebase by porting complete features.
• Set up the mobile CI/CD pipeline from scratch using GitHub Actions for build, test, and deploy.
• Integrated an AI chat feature by connecting Flutter UI to a backend-provided service via Method Channels.
• Migrated existing native functionality to Flutter via Method Channels while ensuring functional parity across platforms.
• Wrote unit tests covering business logic and migrated modules, including Kotlin code migrated from Java.
• Configured Fastlane lanes for automated build and deployment as part of the CI/CD pipeline.
• Integrated Firebase across both Android and iOS codebases.

A corporate fitness competition platform integrating Apple Health, Google Fit, and Garmin for activity tracking across teams.

• Developed frontend-focused features across Flutter mobile, Flutter Web admin panel, and Node.js backend within a team of 5.
• Built admin panel modules for race and competition result display and team management.
• Integrated Garmin Health API for activity data synchronization.
• Integrated Garmin Health API to pull activity data including steps, heart rate, and workout history.
• Developed team and competition management modules in the Flutter Web admin panel.
• Contributed to the Node.js backend alongside two other full-stack developers.

An e-commerce app for a Ukrainian publisher known for the Ukrainian Lord of the Rings translation, featuring a custom audiobook player and book reader.

• Developed and maintained a cross-platform Flutter application for iOS and Android.
• Wrote native audiobook player and book reader implementations in both Kotlin and Swift and integrated them into Flutter via Method Channels.
• Integrated Google Pay and Apple Pay payment flows.
• Designed and implemented a feature-first architecture for scalability and team autonomy.
• Built custom native audio and reading engines in Kotlin and Swift and bridged them to Flutter via Method Channels.

A cross-platform mobile e-commerce application for iOS and Android, developed within a team of 30 people.

• Led a sub-team of 3 developers by conducting code reviews, mentoring junior developers, and coordinating with backend and design teams.
• Developed and maintained frontend features using Flutter with BLoC state management.
• Collaborated on architecture decisions and feature delivery across the full mobile stack.
• Designed and implemented a feature-first architecture to improve scalability and team autonomy.
• Integrated a custom OpenGL-based 3D engine into the Flutter application using Method Channels.
• Implemented the GraphQL data layer using graphql_flutter with AWS Amplify and Cognito for authentication.
• Built a custom navigation system on top of Flutter Navigator, replacing third-party routing packages.
• Developed a full hybrid design system combining Material and Cupertino principles with a custom widget library to ensure consistent UI across iOS and Android.
• Set up the push notification delivery pipeline via AWS SNS.