Gergely – Kotlin, Android, Java

An Android-based payment terminal application enabling merchants to process card and Bitcoin transactions through unified payment workflows. The solution supports refunds, transaction recall, receipt printing, end-of-day reconciliation, and integration with electronic point-of-sale (ePOS) systems. It also provides secure telemetry capabilities to support payment operations and troubleshooting.

• Integrated multiple payment processors and merchant acquirers to support card and Bitcoin transactions;
• Developed ePOS integration capabilities, including supporting APIs and frontend interfaces;
• Implemented end-of-day reporting, refunds, transaction recall, and automatic sign-in workflows;
• Built telemetry capabilities with encrypted, role-based access to support operational monitoring and troubleshooting;
• Integrated native Android device capabilities, including receipt printing with customizable layouts;
• Created release testing plans to validate application functionality and payment workflows;
• Owned Android application development and managed releases.

A mobile fintech application enabling users to buy and sell Bitcoin through instant purchases, recurring investments, and limit orders. The platform supports multiple custody options, including self-custody, managed vaults, and tax-advantaged retirement accounts, alongside educational content to help users learn about Bitcoin.

• Developed the Bitcoin price chart feature end-to-end, implementing both the API and Flutter mobile interface;
• Improved code generation workflows and CI/CD integration to support application development and delivery;
• Optimized screen transitions to improve application responsiveness and navigation performance;
• Enhanced application telemetry using Datadog to support operational monitoring and troubleshooting;
• Contributed to the development of a new user onboarding flow.

A mobile health and wellness application designed to help users build healthy habits through mood tracking, guided meditation, physical activity planning, and self-care coaching. The platform combines mental wellness and fitness features, including personalized exercise plans and video content, to support a balanced lifestyle.

• Led the migration of existing native mobile applications to a unified React Native codebase;
• Developed a native module for Google Fit integration to support fitness-related functionality;
• Implemented the exercise video planning feature within the mobile application;
• Built a native module for casting content to TV devices and integrated it with the exercise video planning feature;
• Managed Android application releases through Google Play Store.

Development and modernization of native Android applications for multiple clients across healthcare, education, travel, sports streaming, and social wellness. The projects included a health and fitness application with mood tracking and guided exercises, an educational platform for attendance and class management, an airline booking application, a sports media streaming platform, and a wellness-focused social application prototype.

• Led a team of four Android developers on a health application, achieving feature parity with the existing iOS version within six months;
• Integrated AI-based pose detection features and reduced the health application's size by approximately 70% using On-Demand Resources;
• Led two junior developers on an education platform, implemented core functionality, and initiated offline support;
• Improved application stability and implemented state restoration across airline booking workflows;
• Enhanced sports streaming reliability across device orientations and updated existing screens to match a redesigned interface;
• Developed a mood selection UI component and contributed to core functionality for a wellness-focused social application prototype