Krystian Wsul, Developer in Málaga, Spain
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Krystian Wsul

Verified Expert  in Engineering

Material Design Developer

Málaga, Spain
Toptal Member Since
March 3, 2020

Krystian is a versatile programmer with a focus on Android development. He offers comprehensive Android development services. Krystian can take a project from the initial idea to launching the app to the Google Play Store and handling long-term maintenance and future growth.


Mobile Motion
SQL, Mobile App Development, Firebase, Scrum, Continuous Integration (CI)...
Freelance Work
Video Streaming, Mobile App Development, Video & Audio Processing, GraphQL, SQL...
Mobile App Development, SQL, Swift, Full-stack, Flutter...




Preferred Environment

IntelliJ IDEA, Android Studio

The most amazing...

...thing I've worked on is a social video app, during its growth as one of the leaders in its market.

Work Experience

Android Engineer

2020 - 2021
Mobile Motion
  • Introduced new features into a social video app with over 100 million downloads.
  • Developed advanced video editing functionality, such as filters and video clip composition.
  • Helped transition Java MVP architecture to Kotlin MVI.
  • Participated in a well-organized and mature Scrum process.
Technologies: SQL, Mobile App Development, Firebase, Scrum, Continuous Integration (CI), Video Streaming, Video & Audio Processing, Reactive Programming, Model View Intent (MVI), Model View Presenter (MVP), Google APIs, Room, Dagger 2, GraphQL, RxJava 2, Kotlin, Java, Android, Android Studio

Freelance Full-stack Android Developer

2017 - 2020
Freelance Work
  • Acted as the lead Android developer on a white-label carsharing app with hundreds of thousands of installations across Europe and Asia.
  • Worked as the Android developer on a platform that expedites home delivery from local businesses.
  • Developed an MVP for an app that allows users to view marketing content to collect points, then spend them on ad-free usage in the apps of partnering businesses.
  • Built an Android app for website-sharing social, video-based smartphone reviews.
  • Developed an app for users inexperienced with social media, that facilitates exchanging wishes between friends and family on birthdays, anniversaries, and other life events.
  • Built an Android app for a security contractor to streamline writing collaborative security assessment reports for their employees, annotating them with editable images, videos, and maps; as well as geospatial information.
  • Constructed an MVP Android app and web-based administration tools for a platform that facilitates buying, selling, and exchanging clothing items.
  • Designed an Android app that allows users to coordinate menus for dinner parties.
Technologies: Video Streaming, Mobile App Development, Video & Audio Processing, GraphQL, SQL, Continuous Integration (CI), Full-stack, Model View Viewmodel (MVVM), Model View Intent (MVI), Model View Presenter (MVP), Dagger 2, Accelerometers, Cloud Firestore, JWPlayer, OpenStreetMap API, WhatsApp API,, Mapbox SDK, Near-field Communication (NFC), Reactive Programming, GPS, Realm, Google Location API, Google APIs, Material Design, Firebase Realtime Database, RxJava 2, Android Studio, Bluetooth, Yelp API, Facebook API, Test-driven Development (TDD), Google Drive API, Google Maps SDK, Google App Engine, SQLite, AdMob, Google Cloud Platform (GCP), Firebase, Node.js, Java, Kotlin, Android

Full-stack Developer

2014 - 2017
  • Built an Android application for placing client orders and monitoring delivery progress.
  • Developed an Android application for assisting delivery drivers with order contents and navigation.
  • Redesigned a company's website and online ordering system.
  • Developed desktop software to generate and print customer invoices.
  • Built a type of desktop software to facilitate employee management.
  • Automated synchronizing orders with third-party order and delivery services.
  • Redesigned intranet web tools for restaurant management.
  • Automated email and text message promotional campaigns.
Technologies: Mobile App Development, SQL, Swift, Full-stack, Flutter, Model View Viewmodel (MVVM), Model View Intent (MVI), Model View Presenter (MVP), Dagger 2, IntelliJ IDEA, Reactive Programming, GPS, Google Location API, Google APIs, Material Design, RxJava 2, iOS, Visual Studio, Android Studio, Facebook API, Mobile Payments, Test-driven Development (TDD), Google Maps SDK, Firebase, MySQL, JavaScript, CSS, HTML, PHP, Ruby, MaxDB, ASP.NET, C#, Java, Kotlin, Android

Network Technician

2006 - 2011
University of Wisconsin-La Crosse
  • Automated the deployment of Cisco routers and computer network configurations.
  • Installed and maintained fiber-optic and copper cabling.
  • Performed remote and on-site diagnostics of networked devices.
  • Developed and maintained the networking department's web page.
Technologies: Ruby, Cisco

Release Engineer

2007 - 2010
SAP BusinessObjects
  • Built a centralized build server to replace individual build servers used by seven teams on site.
  • Designed an intranet web page to display build results for all teams.
  • Automated nightly builds along with sending build reports to team managers.
Technologies: SQL, Apache Ant, Perforce, Ruby


The app allows users to lip-sync over audio clips including sections of songs, movies, and famous quotes. Users can upload their own audio and add color filters and text animation to their recordings. Users have to save their clips to their devices and then they can send them via other messaging applications.


A white-label car-sharing app with clients across Europe and Asia that allows renting both private and company-owned cars.

As the lead Android developer, I implemented new features such as support for multiple map providers and payment processing, rebranded the app for individual client companies, and performed general maintenance tasks.


A platform that connects clients to local businesses that have the means to do house deliveries of their products, but don't have their own infrastructure for placing such orders. While the client app is currently available only on iOS, the business app is available in both iOS and Android versions.

As the developer for the Android app, I worked with Google Maps, Mapbox navigation, communicating with the Firebase backend, and implemented a visual redesign of the app.


An Android app for a platform that allows users to post and browse video reviews of smartphones, along with various social media features. The app communicates with both the website backend, as well as a video hosting service.

FireWatch Solutions (Internal-use App)
FireWatch Solutions provides a variety of private security services for people traveling to high-risk parts of the world. This app allows on-site employees to collaboratively build reports about the client's destination. This includes recording multimedia and geospatial information about various venues the client plans to visit, building maps of the area, and creating custom graphical elements such as drawing floor plans.

An Android app that serves as a complex metronome for musical practice with advanced features such as combinations of time signatures.

Over the years, I have implemented new features, app redesigns, and performed general maintenance.

MaxiPizza is a pizza restaurant chain that I have been working with for a few years.

Among other things, I have built their back end, website, and matching Android app. The whole set spans numerous platforms, including Windows and Unix servers, a variety of databases and communication protocols and web- and Android-based client apps.


Kotlin, Java, SQL, C#, HTML, CSS, Swift, GraphQL, PHP, JavaScript, Ruby


RxJava 2, Google Location API, Google APIs, Google Maps SDK, Google Drive API, Node.js, Facebook API, OpenStreetMap API, Yelp API, WhatsApp API, Accelerometers


Android Studio, Visual Studio, IntelliJ IDEA, Perforce, Apache Ant, JWPlayer,


Model View Presenter (MVP), Model View Viewmodel (MVVM), Reactive Programming, Model View Intent (MVI), Test-driven Development (TDD), Continuous Integration (CI), Scrum


Android, Firebase, Google Cloud Platform (GCP), Google App Engine, iOS


Firebase Realtime Database, MySQL, SQLite, Realm, MaxDB, Cloud Firestore


Full-stack, Mobile App Development, GPS, Video & Audio Processing, Video Streaming, Material Design, AdMob, Cisco, Room, Near-field Communication (NFC), Mapbox SDK, Mobile Payments, Bluetooth


ASP.NET, Dagger 2, Flutter

2006 - 2010

Bachelor of Science Degree in Computer Science, Mathematics, Physics

University of Wisconsin-La Crosse - La Crosse, WI, USA

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