Juraj Kušnier

email: jurajkusnier@gmail.com

I'm a passionate Mobile Android Developer since Android 2.3 (ca. 9 years). I have created many mobile apps using native ( Kotlin / Java ) and cross-platform ( Flutter / Unity3D ) technologies. Nowadays, I work as a Freelance Android Developer.

Highlighted Projects

Corona-Warn-App

Android App

The Corona-Warn-App is an app that helps trace infection chains of SARS-CoV-2 (which can cause COVID-19) in Germany. The app is based on technologies with a decentralized approach and notifies users if they have been exposed to SARS-CoV-2. It is the main corona app for Germany, where it is interconnected with the national health care system. Great emphasis is placed on data protection and transparency since the mobile app handles the sensitive health data of users. The project is open-source and available on GitHub.

I worked on this project as an external contractor 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 really helped many people and most likely saved some lives.

Technologies: Kotlin, Exposure Notification API, Coroutines, Material Design, Dagger 2, Room, Retrofit, WorkManager, DataStore, JWT, Bouncy Castle, and more

Holidu: Search engine for vacation rentals

Android App

Holidu is one of the fastest-growing travel tech companies worldwide. It's based in Munich, Germany, and provides a vacation rental meta-search engine.

During more than 2 years in the company, I have converted the original Java codebase of the Holidu Android App to Kotlin, increased test coverage, cleaned the app architecture, and introduced dependency injection to the project. I developed many challenging features like google sign-in, theme-based search, or image classification using machine learning (hackathon project). I improved the look and feel of the app by implementing the Material design components, fancy transitions, and animations.

Technologies: Java, Kotlin, MVVM, MVI, RxJava, Retrofit, Room, Coroutines, Push-Notifications, Hilt, Firebase, Jenkins and more

Minesweeper Classic

Android Game

Minesweeper is a mobile version of a well-known puzzle video game. The game has more than 2,000,000 downloads and very good user reviews. The objective of the game is to clear a rectangular board containing hidden "mines" or bombs without detonating any of them, with help from clues about the number of neighboring mines in each field.

I closely monitor the app with tools like firebase analytics to better understand how users use the app and crashlytics to quickly detect new issues. I use A/B testings and staged rollouts before publishing major changes and new features. One of the major features I've added to the app was Google Play Instant, where people can tap to try an app without installing it on their phones.

Technologies: Java, Kotlin, Firebase, AdMob, Google Play Instant, and more

Wealth Check - Bitcoin Wallet Balance and History

Open source android app

Wealth Check allows you to check the balance and history of any bitcoin wallet. Just scan the bitcoin address QR code to see all important information like bitcoin balance, fiat balance by current conversation rate, transactions history, etc. All scanned wallets are safely stored on your phone for offline access. You can sort wallets in the favorites list.

The app is written in the Kotlin programming language. It's my open source project and the source code is available on GitHub. I have chosen the MVVM pattern for the main app structure. I have implemented part of Android Architecture Components and libraries like RxJava, Retrofit, Dagger 2, Moshi, etc. Feel free to contribute.

Technologies: Kotlin, Android Architecture Components, Hilt, Retrofit 2, Room, Moshi, Coroutines, and more

Nature and Relaxing Sounds

Open source android app

The project follows Media app architecture guidelines. It uses Android MediaPlayer to play audio files saved in the assets folder. Playback is available on Android Phones as well on Android Auto and the new Android Automotive OS.

The app is written 100% in Kotlin programming language. The project is open-source and available on GitHub.

Submarine Dash

Android & iOS Game

Submarine Dash is a 3D arcade game designed for Android and iOS mobile devices. The player leads a small submarine to explore the ocean and collect lost treasure. I have created the game using the Unity 3D game engine.

Just Turn Right

Android & iOS Game

Just Turn Right is a 3D puzzle-casual game designed for Android and iOS mobile devices. The main features of the game are one-finger control, demanding puzzles, and fast and challenging gameplay. I have created the game using the Unity 3D game engine.

More apps and games are on Google Play Store and iTunes App Store

Experience

Freelance Android Developer

SAP, Munich

I worked as Freelance Android Developer on the Corona-Warn-App, the main corona app for Germany. Even though the project was challenging in many ways, it was also a great experience as we really helped many people and most likely saved some lives.

January 2021 - Present

Android Developer

Holidu GmbH, Munich

During more than 2 years in the company, I have converted the original Java codebase of the Holidu Android App to Kotlin, increased test coverage, cleaned the app architecture, and introduced dependency injection to the project. I developed many challenging features like login, theme-based search, or image classification using machine learning (hackathon project). I also had the opportunity to help with backend development in the Java Spring Boot framework during difficult times.

September 2018 - December 2020

CEO & Lead Mobile Developer

Verusoft, s.r.o, Bratislava

I founded Verusoft to be able to work on my own ideas in a more professional way. I released many successful android and iOS apps and games with more than 3,000,000 downloads and very positive user reviews. I was one of the early adopters of the Android Instant App and worked closely with the Android Instant Apps team from Google on implementing this feature.

August 2015 - September 2018

Android Developer

Foundation, s.r.o, Bratislava

I was developing an android app Soonr Go (later rebranded to Autotask Workplace Mobile). The mobile app provides secure access to the user's content, allows them to create and edit files, and sync all changes between other clients. Android and iOS clients shared the same core written in C so the app was heavily using Java Native Interface (JNI).

April 2014 - November 2015

Software Developer

Siemens Convergence Creators, Brno

I worked as a Javascript and Smart TV developer of a multi-platform OTT (Over-the-top) media service. I participated in the development of a media application providing DRM protected audio and video content over the Internet. For a short time, I worked also as a scrum master.

June 2013 - March 2014

Software Developer

Geodis Calberson, Bratislava

I was part of a small team developing automatic invoice verification software. The software was used internally by employees of Geodis Calberson to automate and improve invoice processing.

December 2010 - June 2011

Education

Brno University of Technology

Faculty of Information Technology

Interrupted study

2011 - 2013

Slovak University of Technology in Bratislava

Faculty of Informatics and Information Technologies

Bachelor’s degree in Information Technologies

2008 - 2011

Skills

Mobile development
  • Android SDK & NDK
  • UI/UX Design
  • A/B testing
  • App Store Optimization (ASO)

Programming Languages
  • Kotlin
  • Java
  • C#
  • JavaScript

Tools
  • Android Studio
  • Unity 3D
  • XCode
  • Git

Workflow
  • Clean Code
  • Android First
  • Agile Development & Scrum
  • Continuous Integration and Continuous Delivery

Interests

Apart from being a software developer, I prefer spending some time outdoors, biking, swimming, and skiing to maintain a healthy lifestyle.

On the other hand, I spend a large amount of my free time exploring the latest technological advancements, learning new stuff, and improving my skills.