Zoltan Varadi, Developer in Szeged, Hungary
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Zoltan Varadi

Verified Expert  in Engineering

Software Developer

Szeged, Hungary
Toptal Member Since
October 29, 2015

As a user experience enthusiast, Zoltan's greatest strength as an engineer is his precise design implementation. He has a positive attitude and an open mindset that enable him to bring the best quality projects to life. Zoltan's experience in maintaining a relationship with customers and managing team workflow help him to provide the best overall value to his team.


PetrolPrices.com Ltd (via Toptal)
Storyboarding, REST APIs, RESTful Development, Interface Builder, Swift...
Kalon Creative (via Toptal)
Swift, Alamofire, UIKit, ZURB Foundation, Swift 3
Perchwell (via Toptal)
Fabric, Mixpanel, SnapKit, iOS Charts, SDWebImage, Alamofire, Auto Layout...




Preferred Environment

GitHub, Interface Builder, Swift, Xcode

The most amazing...

...feeling was receiving written consent from NASA to publish my pet project, Apollo Archive to the iTunes App Store.

Work Experience

iOS Developer

2016 - 2016
PetrolPrices.com Ltd (via Toptal)
  • Created a pixel perfect design implementation that scales well on all iPhone devices for new features.
  • Identified performance issues causing high network consumption and fixed them.
  • Created reusable components in Swift, merged it in the Objective-C based environment.
  • Simplified the app by removing unused features, merging menu items together, adding an in-app web browser, and improving the on-boarding flow.
Technologies: Storyboarding, REST APIs, RESTful Development, Interface Builder, Swift, Objective-C

iOS Developer

2016 - 2016
Kalon Creative (via Toptal)
  • Upgraded an existing iOS app from Swift 1.2 to Swift 3.
  • Replaced deprecated function calls with their newest versions.
  • Added minor changes requested by the client.
  • Versioned the source code in each step of the upgrade process under separate branches using git.
Technologies: Swift, Alamofire, UIKit, ZURB Foundation, Swift 3

Senior iOS Developer

2015 - 2016
Perchwell (via Toptal)
  • Created a pixel perfect design implementation that scales well on all iPhone devices.
  • Identified performance issues causing choppiness in the user experience and fixed them.
  • Optimized memory and CPU time management.
  • Implemented complex data visualization using 15+ different chart types.
Technologies: Fabric, Mixpanel, SnapKit, iOS Charts, SDWebImage, Alamofire, Auto Layout, Interface Builder, Swift

Lead iOS Developer

2013 - 2015
Red Steed Studios
  • Learned how to divide projects into tangible tasks and how to simplify and execute these projects while allowing space for changes.
  • Used several third party services, such as Facebook, Google, Imgur, Amazon S3, Branch.io, etc.
  • Took part in projects actively as a Developer and as a Development Team Leader.
Technologies: Web Technologies, Transport Layer Security (TLS), Location Services, REST, Protocol Buffers, Auto Layout, Interface Builder, Core Data, Objective-C

iOS Developer

2012 - 2014
Pronovix Hungary
  • Worked as a Full-stack Developer.
  • Maintained a relationship with clients.
  • Managed project requirements such as design, implementation, testing, and follow-up.
  • Developed an iOS application with its PHP based back-end for a coffee shop.
  • Created an application for mechanical watch owners to keep track of their device's accuracy and set their time using atomic clocks.
Technologies: Network Time Protocol (NTP), Git, JSON, REST, Drupal, Core Data, Objective-C

C++ Developer

2010 - 2012
GE Healthcare
  • Implemented clinical research applications to find lung and liver cancer in CT images.
  • Improved the speed of a tumor searching algorithm by 90%.
  • Became co-author of a worldwide patented workflow for finding tumors in the liver organ in CT images.
  • Created and implemented an algorithm for better visualizing cancerous areas in the lung area in CT images.
Technologies: Image Processing, C++

Apollo Archive

Apollo Archive is an app for space enthusiasts. It helps its users to browse through all images taken during the Apollo missions and enjoy them in high resolution. What makes this app special to me is the written consent I received from NASA to publish the app freely to the app store.

With this app, I wasn't exclusively the developer, however I did the UI/UX design myself. My goal was to gain first-hand experience with product development from ideation to production, and to become familiar with all aspects of a product's lifecycle.

PetrolPrices (via Toptal)

PetrolPrices.com is the largest fuel price comparison service in the United Kingdom. I had the privilege to improve the existing app's functionality, and increase its performance and stability.

NYC Apartments by Perchwell (via Toptal)

Perchwell is an iOS application for finding real-estate in Manhattan, New York. It offers a great interface for filtering suitable properties, comparing them, and calculating expenses. The application also helps to analyze the real-estate market with various charts.


Dryft is an application for hikers who don't want to get lost when they go into the wilderness. It keeps a constant record of their whereabouts, notifies them if they have gone too far or too long, and guides them back to where they started.


As a consultant, helped the Ntice team to improve their existing application.

My First International Presentation Session at iOSDevUK

I had the honor of speaking about third party tools and practices at one of Europe's biggest conference.
2016 - 2016

Various Certificates in Aerospace Engineering

MIT, ESA - Online

2011 - 2013

Master's Degree in Computer Engineering and Image Processing (unfinished)

University of Szeged - Szeged, Hungary

2006 - 2011

Bachelor's Degree in Computer Engineering

University of Szeged - Szeged, Hungary


Mapbox iOS SDK, Google Maps SDK, REST APIs, Core Animation, Fabric, Flickr API, Google Maps Premium Roads API, Firebase Web SDK, iOS Charts, Facebook iOS SDK, Alamofire, SDWebImage, SnapKit, Facebook API


Auto Layout, Git, Sketch, Interface Builder, Fastlane, Crashlytics, Xcode, GitHub, Pivotal Tracker, Adobe Illustrator, Adobe Photoshop


Core Location, Core Data, ZURB Foundation, UIKit


Swift 4, Swift 3, Swift 2, Swift, Objective-C, GraphQL, C++, JavaScript, Java


RESTful Development, Responsive Development, Agile Software Development, REST


Back4App, Parse, iOS, Firebase, Drupal, Mixpanel




Pixel Perfect, User Experience (UX), User Interface (UI), 3D Image Processing, Medical Imaging, Image Processing, Network Time Protocol (NTP), Location Services, Transport Layer Security (TLS), Web Technologies, Storyboarding, Presentations, Protocol Buffers

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