Juraj is an experienced senior software engineer and Android app developer focusing on products and a high-quality user experience. In the last 10+ years, he worked on critical projects for small and large clients, banks, and government agencies and shipped apps for tens of millions of users. Juraj knows how to deal with large legacy systems and quickly and effectively set up and launch greenfield apps.
ExperienceJava - 10 yearsAndroid - 10 yearsAndroid Development - 10 yearsKotlin - 5 yearsCoroutines - 4 yearsModel View Intent (MVI) - 2 yearsJetpack Compose - 2 yearsKotlin Multiplatform Mobile (KMM) - 2 years
MacOS, IntelliJ, Android Studio, Git
The most amazing...
...project I’ve worked on is the official Corona-Warn-App for Germany, which helped slow down the spread of COVID-19 infections and most likely saved many lives.
Senior Android Developer
Trade Republic Bank GmbH
- Implemented critical features for credit card processing.
- Improved the overall UI and UX of a mobile app using the latest technologies, such as Android Jetpack.
- Implemented multiple successful A/B tests. Increased app engagement and user retention.
Senior Android Developer
- Developed an app that helps trace infection chains of SARS-CoV-2 (which can cause COVID-19). Used the exposure notification API from Apple and Google.
- Implemented and maintained critical features according to the requirements of the German government.
- Created an automated screenshots pipeline using Firebase, which handled multiple languages and screen configurations.
- Maintained an open-source project and took care of open issues and PR reviews.
- Developed many challenging features like login, in-app bookings, and a theme-based search. Increased app engagement and overall app revenue.
- Implemented image classification using machine learning running on mobile devices during the company hackathon.
- Designed and implemented multiple REST APIs endpoints and microservices using the Spring Boot framework.
- Migrated the legacy Java code base to Kotlin and increased testability, app stability, and test coverage.
- Cleaned the app architecture and introduced dependency injection to the project.
Lead Mobile Developer
- Led a small team of programmers and designers. Built multiple successful mobile apps and games with more than 3,000,000 downloads and positive user reviews.
- Worked closely with the Android Instant Apps as an early adopter. Worked with Google on implementing this feature.
- Handled the entire software development life cycle, from the idea to the app design, implementation, launch, marketing, and maintenance.
- Worked on an Android client for one of the first B2B file synchronization platforms called Soonr Go, Acquired by Autotask Corporation.
- Built the front end of an Android app using a synchronization library written in C++.
- Accomplished big refactoring and a migrated legacy C++ core library to Java.
Siemens Convergence Creators (Atos)
- Developed a multi-platform service for smart TV and web.
- Implemented digital rights management to manage legal access to digital content.
- Led the migration of a multi-media streaming service from the web to various smart TV devices.
Trade Republic: an Android Mobile Broker Apphttps://traderepublic.com/
I worked for Trade Republic as a freelance mobile developer together with a big team of internal developers. I implemented multiple successful experiments and improved the overall UI and UX of the mobile app using the latest technologies, such as Jetpack Compose.
Holidu: an Android Accommodation Apphttps://www.holidu.com/
During more than two years in the company, I have converted the original Java codebase of the Holidu Android app to Kotlin. I increased test coverage, cleaned the app architecture, and introduced dependency injection to the project. I also developed many challenging features like Google Sign-in, theme-based search, and image classification using machine learning (hackathon project). In addition, I improved the look and feel of the app by implementing material design components, fancy transitions, and animations.
Corona-Warn-App: an Android Coronavirus Apphttps://www.coronawarn.app/en/
I worked on this project as a freelance developer and helped to implement many features, tests, and bug fixes. Even though the project was challenging in many ways, it was also a great experience as we helped many people and most likely saved some lives.
Nature and Relaxing Soundshttps://github.com/jurajkusnier/relaxing-sounds
Flutter, Android SDK, JNI, Dagger 2, JSON Web Tokens (JWT), AngularJS, Media Player, Mockito, JUnit, Spring Boot, Unity3D
RxJava, RxJava 2, REST APIs, Retrofit 2, Google AdSense, WorkManager API, Protobuf, Camera API, TensorFlow, Android API, Material 2, WebRTC
Android, Mobile, Firebase, iOS, Amazon Web Services (AWS), DigitalOcean
Android Development, Mobile App Development, Networking, Jetpack Compose, User Interface (UI), Coroutines, Subscriptions, Kotlin Multiplatform Mobile (KMM), APIs, User Experience (UX), HTTP, Authentication, Integration, Android Architecture, Android Animations, VoIP, Audio Streaming, Video Streaming, Computer Networking, Informatics, Software Development, Material Design, A/B Testing, Open Source, Room, Hilt, Google Play Store, App Store, Google AdMob, In-app Purchases, Java Native Interface (JNI), Smart TV, Over-the-top Content (OTT), Digital Rights Management (DRM), Exposure Notification System, Machine Learning, CI/CD Pipelines, Push Notifications, Code Review, Source Code Review, Data Encryption, UI Testing, Espresso, QR Codes, Bluetooth, API Design, Back-end, Back-end Development, Image Recognition, Integration Testing, Cross-platform App Development, APK, Game Design, Game Development, Team Leadership, Encryption, Cross-platform Libraries, File Sharing, Roku, Widevine, QA Testing, OAuth, SSL, SSL Certificates, Video on Demand (VOD), Audio, Notification Center, WebSockets
Git, Android Studio, GitHub, Android Jetpack, Grafana, Kibana, Unity SDK, Android NDK, Subversion (SVN), Jenkins, SonarQube, Gradle, IntelliJ IDEA, Fastlane, Crashlytics, Android Auto, Figma
Model View Intent (MVI), Model View Viewmodel (MVVM), Test-driven Development (TDD), Behavior-driven Development (BDD), Design Patterns, Android Material Design, Dependency Injection, REST, App Store Optimization (ASO), Continuous Integration (CI), Continuous Delivery (CD), Unit Testing, Microservices, Cross-platform, B2B, Scrum
Databases, Elasticsearch, SQLite, RoomDB, Amazon S3 (AWS S3), JSON
Bachelor's Degree in Information Technology
Slovak University of Technology - Bratislava, Slovakia