Hande Oktay

• Responsible for designing, developing, and maintaining innovative payment and transaction-based applications for Android POS devices and mobile platforms.
• Lead the development of secure, high-performance solutions utilizing Kotlin, Java, and Jetpack Compose. Employ modern architectural patterns like MVVM, and integrate tools such as Retrofit, Room, RxJava and Coroutines for seamless functionality.
• Collaborate throughout the full development lifecycle, from initial design to final deployment and ongoing support, ensuring alignment with customer requirements and enhancing user experience.
• Implement robust security measures with encryption algorithms.
• Ensured application compatibility across multiple Android devices and OS versions through rigorous testing efforts, optimizing performance for various screen sizes and hardware configurations.
• Enhanced user experience by developing visually appealing and intuitive Android applications.
• Ensure application reliability and performance through comprehensive testing strategies, including unit, integration, and UI testing.
• Used specific code versioning tools to manage and implement changes to programs.
• Track app performance and identify issues using Bugsnag, Google Analytics, and Crashlytics to ensure optimal reliability and performance.
• Defined, created and maintained technical and user documentation, test cases and release notes.
• Mentored junior developers on best practices in Android development, fostering a collaborative team environment focused on continued learning.
• Estimated work hours and tracked progress using Scrum methodology.

Projects

• Fuel Card & Payment System

- Developed an Android POS device app integrating Mifare Classic cards through NFC, using Kotlin, Coroutines, Room, Retrofit, MVVM architecture, Hilt, Data Binding, and implementing RSA and AES encryption for security. Application manages fuel station cashiers and management's requirements such as payment processing, generating reports, handling shifts, receipts, and other administrative tasks.

- Developed the Android app with features for users to manage fuel cards, track transactions and make payments via QR code and NFC.

- Implemented push notifications and background services to provide real-time updates and alerts for transaction statuses and card activities.

- Fully designed the UI for the fuel card apps using Adobe XD, focusing on an intuitive and seamless user experience to meet customer expectations.

- Created detailed test cases and scenarios to cover a wide range of user interactions, including edge cases and error handling. Implemented unit tests, integration tests and ui tests.

- Successfully launched and managed the system, now operational in Azerbaijan fuel stations, handling thousands of transactions daily.

• Mobile Wallet Application

- Led a team to develop a mobile wallet app featuring multi-currency user accounts, invoice payments, and QR code payments.

- Utilized MVVM architecture with LiveData, ViewModel, and Data Binding for efficient state management and UI updates.

- Implemented security protocols including biometric authentication and token-based authorization and encryption algorithms for secure communication.

- Utilized Glide for image loading and caching to enhance app performance and user experience.

- Contributed to the design of the wallet app, using Figma to create visually appealing and user-centric interfaces that align with customer requirements.

- Used Firebase Test Lab to test the app on a wide variety of real devices hosted in the cloud, ensuring compatibility and performance across different hardware configurations.

Notes: I also lead the iOS application development of this app using Swift and SwiftUI, integrating Core Data for local storage, CryptoKit and Keychain for security and Alamofire for networking.

• Government Payment Portal Invoice Application

- Developed and maintained a Government Payment Portal invoice application for Android POS devices using Java .

- App communicates with the government invoice system to retrieve invoices and enables users to search for invoices and make payments through banking apps installed on the same Android POS device.

- Used RESTful APIs with Retrofit for backend communication and implemented caching strategies with DBFlow database to optimize performance.

- Designed an intuitive user interface using Adobe XD to facilitate easy invoice search and payment processing.

- System is successfully launched and still used in many merchant Android POS devices and handling many invoice payments daily.

• Sales Application

- Transitioned the Sales Application to Kotlin Multiplatform, enabling shared code between Android and iOS.

- Implemented UI components using Jetpack Compose, enhancing performance and reducing boilerplate code.

- App has features to manage merchants' needs, including product management, pricing, receipts, reports, transactions, and payments.

- Enhanced application performance with Coroutine-based concurrency and improved user experience with dynamic UI updates using LiveData and Flow.

- Utilized Retrofit for API integration and Room for local database management.

• Other

- Also contributed to various parts of existing applications, such as banking apps that process EMV data and communicate with bank hosts.

- Added numerous functionalities to the company's core library, which includes multiple modules for use across different projects. This core library includes utility classes, POS-specific APIs and interfaces, communication modules (including sockets and Bluetooth protocols), and more.

- Additionally, assisted in the development of iOS applications such as the mobile wallet app and fuel card app.

- Used Bitbucket for source control, Jira for managing Scrum boards and ensuring an agile environment, and Bamboo for automating builds and releases.

• Worked with a team of 4 developers in creating a sport facility booking app for a client, contributing to both design and development phases.
• Attended all client meetings to ensure clear communication and understanding of requirements, facilitating smooth project progress.
• Used Java programming language and followed MVVM architecture to enhance code organization and maintainability.
• Developed features including facility information display, available booking slots management, friend requests handling, and group booking appointment functionalities.
• Implemented Socket.IO for real-time communication features such as chat with friends and live updates.
• Implemented Retrofit for RESTful API integration, ensuring efficient data retrieval and synchronization.
• Used Glide for efficient image loading and caching to optimize app performance.
• Integrated Room database for local storage, ensuring seamless data persistence and management.
• Conducted comprehensive unit testing to validate business logic and ensure code reliability.

• Collaborated on the development of a 2D platformer game for Android using the company’s proprietary framework.
• Designed levels, implemented game physics, used SurfaceView and created UI screens in collaboration with a project partner.
• Contributed to the integration of game mechanics and player interactions, ensuring smooth gameplay experience.
• Participated in daily team meetings and code reviews to refine development processes and improve game performance.
• Improved overall game quality with thorough playtesting, identifying areas needing improvement or adjustment.
• Gained hands-on experience in debugging, optimizing, and testing the game across different Android devices.