Janusz Gregorczyk, Software Developer in Szczecin, Poland
Janusz Gregorczyk

Software Developer in Szczecin, Poland

Member since August 20, 2014
Janusz is an experienced iOS developer who has developed more than 40 iOS apps from scratch over the last few years while working on many more. Before that, he was a co-founder of Gameleons (in its prime time, one of Poland's biggest mobile development teams) and worked on over 50 mobile Java games.
Janusz is now available for hire


  • Doist
    Swift, iOS
  • codesize
    Cocos2d, OpenGL, Instruments, UIKit, Git, iOS SDK, Objective-C
  • Bright Mediums
    Multithreading, Core Data, iOS SDK, Objective-C



Szczecin, Poland



Preferred Environment

Git, Xcode

The most amazing...

...thing I've coded was a Doom-style game engine in mobile Java.


  • iOS Developer

    2014 - PRESENT
    • Developing iOS apps in Swift.
    Technologies: Swift, iOS
  • Independent software developer (self-employed)

    2008 - PRESENT
    • Worked remotely with businesses worldwide.
    • Specialized in mobile application development, particularly the iOS platform.
    • Developed about 40 iOS applications from scratch and worked on many more.
    Technologies: Cocos2d, OpenGL, Instruments, UIKit, Git, iOS SDK, Objective-C
  • Senior iOS Engineer

    2013 - 2014
    Bright Mediums
    • Developed and maintained of several challenging iOS projects.
    • Worked in an Agile team.
    • Provided expertise in multithreaded CoreData, CoreLocation, UIKit.
    Technologies: Multithreading, Core Data, iOS SDK, Objective-C
  • Senior iOS Developer

    2013 - 2014
    AppwoRx LLC
    • Worked on a 2.0 version and subsequent enhancements of a clinical photography application.
    • Almost completely rewrote the iOS code base, developing an iOS universal application, heavily interfacing with a REST-ful back end.
    Technologies: REST, Interface Builder, CocoaPods, iOS SDK, Objective-C
  • Mobile Hero

    2010 - 2013
    Brothers Media
    • Developed several beautifully designed iOS universal applications featuring in-app purchases, maps, and push notifications.
    Technologies: In-app Purchases, MapKit, Core Location, Core Animation, UIKit, Objective-C
  • CTO, Co-founder

    2005 - 2008
    Gameleons Sp. z o.o.
    • Managed development and R&D activities of one of Poland's top mobile game studios of the time.
    • Involved in over 40 J2ME projects, from conception to post-production maintenance.
    • Developed several game engines, a local Bluetooth multiplayer solution, and a core porting technology.
    Technologies: Continuous Integration (CI), Python, Java, J2ME
  • C/C++ Programmer / Contractor

    2003 - 2004
    InterActive Vision Mind Beacon Sp. z o.o.
    • Helped port two arcade simulator games from PC to the PlayStation 2 platform: Operation Air Assault and Pacific Warriors 2.
    • Worked on platform and compiler porting of large Visual C++ code base to PS2 and GCC.
    • Implemented PS2-specific features.
    • Performed subsequent optimization and bug fixing.
    Technologies: Subversion (SVN), RenderWare, PlayStation, GCC, Microsoft Visual C++, C++, C
  • C/C++ Programmer

    2001 - 2003
    InterActive Vision Mind Beacon Sp. z o.o.
    • Programmed a variety of applications on Palm OS and Windows Mobile.
    • Developed game back end, parts of user interface and various other components of the PC game Airlines 2.
    Technologies: Subversion (SVN), Pocket PC, Palm OS, WinAPI, Microsoft Visual C++, C++, C


  • Zonnesimulator for Eneco

    Solar panel planner / calculator for an international sustainable energy company.

    I worked on UIDocument-based renewable energy calculator and used complex CoreAnimation transforms.

  • RxPhoto for AppWorks LLC

    I was responsible for the 2.0 release of this clinical photography application. It was an almost-total rewrite of the iOS codebase, developing an iOS universal application heavily interfacing with a REST-ful backend.

  • Ahold Experience for Ahold Europe

    Corporate training/gamification app.

    Used Vuforia SDK, OpenGL, and AVFoundation for AR video display.

  • The Bovenkant van Nederland for Scriptum Publishers

    Aerial photography album.

    Developed a custom interface with lots of CoreAnimation, MapKit, IAPs, CoreLocation.

  • Dinosaurs for Kids for Potrus Publishing Sp. z o.o.

    Interactive book based on custom OpenGLES/C++ engine with Lua and Box2D.


  • Languages

    C, Objective-C, C++, JavaScript, Python, Java, C#, Swift
  • Frameworks

    ZURB Foundation, UIKit, Cocoa, AFNetworking, Core Data, Cocos2d, iOS SDK, Core Location, MapKit
  • Platforms

    iOS, J2ME, PlayStation, Android
  • Libraries/APIs

    Core Animation, Parse SDK, CocoaPods, OpenGL, WinAPI
  • Tools

    Instruments, Interface Builder, Microsoft Visual C++, GCC, Subversion (SVN), Bitbucket, GitHub, Git, TextWrangler, Xcode
  • Paradigms

    Continuous Integration (CI), REST
  • Other

    Multithreading, In-app Purchases, RenderWare, Palm OS, Pocket PC, AVFoundation


  • MSc Degree in Electronics Engineering
    1999 - 2004
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie - Szczecin, Poland

To view more profiles

Join Toptal
Share it with others