Stefan Kaczmarek, Developer in Phoenix, AZ, United States
Stefan is available for hire
Hire Stefan

Stefan Kaczmarek

Verified Expert  in Engineering

AVFoundation Developer

Location
Phoenix, AZ, United States
Toptal Member Since
October 12, 2017

Stefan is a software engineer with 25 years of experience specializing in mobile applications, large-scale software systems, network protocols, encryption algorithms, and audio/video codecs. He has been developing native iOS apps since 2008 and has published several books related to iOS development in both Objective-C and Swift.

Portfolio

OpenReel
iOS, Swift, Objective-C, C++, AVFoundation, SwiftUI, UIKit, REST, WebSockets...
SKJM, LLC
REST, Swift, Objective-C, Mobile Development, iOS SDK, Mobile...
Apriva, LLC
REST, Swift, Objective-C, Mobile Development, Core Bluetooth...

Experience

Availability

Part-time

Preferred Environment

Git, Xcode, MacOS

The most amazing...

...app development experience I've had was when Apple featured my iCam app in their iPhone 3GS "Dog Lover" television commercial.

Work Experience

Mobile Engineering Manager | Mobile Architect

2021 - PRESENT
OpenReel
  • Led the native mobile development of the capture remote video production mobile applications for both iOS and Android.
  • Developed native iOS remove video production mobile applications in Swift and Objective-C utilizing UIKit, SwiftUI, AVFoundation, URLSession (REST), Socket.IO (WebSocekts), Twilio, and OpenTok (WebRTC).
  • Worked with product owners, stakeholders, and designers to define requirements in an Agile Scrum software development environment.
  • Added support for various analog and digital external mobile audio accessories to achieve the highest-quality audio/video recordings possible with a mobile device.
Technologies: iOS, Swift, Objective-C, C++, AVFoundation, SwiftUI, UIKit, REST, WebSockets, WebRTC, Twilio, Twilio Programmable Video, iOS SDK, Architecture, Mobile, Mobile Architecture, TestFlight

Chief Software Architect/Co-Founder

2008 - PRESENT
SKJM, LLC
  • Designed and developed mobile applications for iOS, Android, and Windows Phone using Xcode, Eclipse, and Visual C++.
  • Developed iCam, a mobile application that enables users to remotely monitor multiple live video and audio webcam feeds from a mobile device. iCam has been featured on CNN, Good Morning America, The Today Show, and was chosen by Apple to be featured in the “Dog Lover” iPhone 3GS television commercial.
  • Built iSpy Cameras, a mobile application that enables users to view and control thousands of public video cameras from around the world in real-time from their mobile device. iSpy Cameras held the #1 Paid iPhone App ranking in a number of countries around the world including the UK, Ireland, Italy, Sweden, and South Korea.
  • Designed and developed desktop applications for Mac OS X and Windows using Xcode and Visual C++, as well as the company websites using PHP, MySQL, JavaScript, and CSS.
Technologies: REST, Swift, Objective-C, Mobile Development, iOS SDK, Mobile, Mobile Architecture, TestFlight

Mobile Software Architect

2018 - 2021
Apriva, LLC
  • Led the iOS architecture, design, and development efforts for various mobile payment solutions that support manual entry, magnetic stripe, EMV chip card, and contactless transactions.
  • Developed a mobile payment SDK to give integrating applications the ability to accept mobile payments using various 3rd-party magnetic stripe, chip, and contactless card readers.
  • Developed the AprivaPay Plus EMV-certified mobile payment application for iPhone and iPad and developed mobile payment applications for Global Payments, First Data, iPayment, Wells Fargo, Bank of America, and Valley National Bank.
  • Developed a 3rd-party Bluetooth card reader interface library and integrated other 3rd-party card reader libraries into Apriva's various mobile payment solutions.
Technologies: REST, Swift, Objective-C, Mobile Development, Core Bluetooth, Bluetooth Low Energy (LE), EMV, Credit Cards, Contactless Payment, iOS SDK, Architecture, Mobile, Mobile Architecture, TestFlight

Senior Software Engineer (iOS)

2018 - 2018
Early Warning Services, LLC
  • Provided technical leadership for the architecture and development of the Zelle peer-to-peer mobile payment app for iOS.
  • Led significant refactoring efforts in order to improve maintainability, reduce technical debt, and increase overall app stability.
  • Collaborated with product owners, designers, architects, and developers to design and develop upcoming product features.
Technologies: REST, Swift, Mobile Development, iOS SDK, Mobile, Mobile Architecture, TestFlight

Mobile Software Engineer IV

2015 - 2018
Apriva, LLC
  • Led the iOS architecture, design, and development efforts for various mobile payment solutions that support Manual Entry, Magnetic Stripe, EMV Chip Card, and Contactless transactions.
  • Developed a Mobile Payment SDK to give integrating applications the ability to accept mobile payments using various third-party Magstripe, Chip, and Contactless card readers.
  • Built the AprivaPay Plus EMV-certified mobile payment application for iPhone and iPad, in addition to developing mobile payment applications for Global Payments, First Data, iPayment, Wells Fargo, Bank of America, and Valley National Bank.
  • Created a third-party Bluetooth card reader interface library, in addition to integrating other third-party card reader libraries into Apriva's various mobile payment solutions.
Technologies: REST, Swift, Objective-C, Mobile Development, iOS SDK, Mobile, Mobile Architecture, TestFlight

Chief Technology Officer

2015 - 2015
CodeRed-I, LLC
  • Built and managed the team of in-house iOS & Android software engineers and architects, project managers, business analysts, UI/UX designers, front-end web developers, and graphic artists to design and develop mobile applications and responsive websites.
  • Met with prospective clients, analyzed business requirements, and maintained communication throughout the design and development process.
  • Interfaced with contracted outsourcing companies and conducted weekly status meetings with nearshore software development teams.
  • Led all mobile application design strictly adhering to Apple's Human Interface Guidelines (HIG) and Google's Material Design standards.
Technologies: Java, Android, Swift, Objective-C, iOS, Mobile Development, iOS SDK, Mobile, Mobile Architecture, TestFlight

Senior iOS Engineer

2014 - 2015
LeaseHawk, LLC
  • Architected and developed the multifamily Relationship Management mobile application utilizing RESTful Web Services, SIP internet telephony, remote notifications, and local data storage for the iOS and Android platforms.
  • Participated in the Agile Scrum software development process including daily stand-ups, two-week sprints, and the sprint planning, review, and retrospective meetings.
Technologies: REST, Swift, Objective-C, Mobile Development, iOS SDK, Mobile, Mobile Architecture, TestFlight

iCam - Webcam Video Streaming

https://itunes.apple.com/us/app/icam-webcam-video-streaming/id296273730?mt=8
iCam allows you to monitor multiple live video and audio webcam remote feeds from your iPhone, iPod touch, or iPad over WiFi and EDGE/3G/4G/LTE.

iCam also supports iCam Cloud, a service that automatically backs up iCamSource motion events to the cloud as soon as they are recorded. Event backups can then be easily viewed from iCam or the web if the iCamSource ever goes offline or the computer is stolen.

iCam has been featured on the Today Show, CNN, and Good Morning America in addition to the "Dog Lover" iPhone TV Ad.

Popular uses include baby monitors, pet cams, nanny cams, spy cams, and security cameras.

Record and playback motion events and receive push notifications on your iPhone, iPod touch, or iPad when motion is detected by your iCamSource(s).

iCam Pro - Webcam Video Streaming

iCam Pro is the next generation of our popular webcam viewing app, iCam.

iCam Pro allows you to monitor multiple live video and audio webcam remote feeds from your iPhone, iPod touch, or iPad over WiFi and EDGE/3G/4G/LTE.

iCam Pro also supports iCam Pro Cloud, a service that automatically backs up iCamSource Pro events to the cloud as soon as they are recorded. Event backups can then be easily viewed from iCam Pro or downloaded directly from the web if the iCamSource Pro ever goes offline or the computer is stolen.

iCam has been featured on the Today Show, CNN, and Good Morning America in addition to the "Dog Lover" iPhone TV Ad.

Popular uses include baby monitors, pet cams, nanny cams, spy cams, and security cameras.

Record and playback recorded video events and receive notifications on your iPhone, iPod touch, or iPad when motion or sound are detected by your iCamSource Pro(s).

ipCam - Mobile IP Camera

https://itunes.apple.com/us/app/ipcam-mobile-ip-camera/id440270152?mt=8
ipCam turns your iPhone, iPod, or iPad into a Wi-Fi IP camera.

Features:
• Stream images, video, and audio to compatible applications, including most web browsers and our iCamSource and iCamSource Pro apps.
• Select either the front or back camera.
• Turn the flash on and off via the web interface.
• Adjust the image size, quality, and frame rate.
• Auto-rotate the image based on device orientation.
• Optional date/time image overlay.
• Optional 4:3 aspect ratio image crop.
• Digital pan/tilt the 4:3 cropped image.
• Optional login and password for additional security.
• Tapping the video preview toggles darkening the screen.
• Dynamic DNS support for DynDNS and No-IP users.
• Automatic port forwarding for routers that support UPnP or NAT-PMP.

iSpy Cameras

https://itunes.apple.com/us/app/ispy-cameras/id329506639?mt=8
iSpy Cameras lets you view and control thousands of public video cameras worldwide in real time from your iPad, iPhone, or iPod touch.

iSpy Cameras has been the number one paid app in the UK, Ireland, Italy, Sweden, Korea, and Croatia and the number one paid entertainment app in Japan, Hong Kong, and Australia. iSpy Cameras was among the top 10 best-selling paid entertainment iPad apps in 2010.

iFarkle

https://itunes.apple.com/us/app/ifarkle/id292563688?mt=8
iFarkle is an addictive and entertaining one or two-player version of the dice game Farkle (or Farkel) for the iPhone and iPod touch. Play with a friend or against the computer to be the first to achieve more than 10,000 points by rolling the dice for an exciting number of different scoring combinations.

Two-player mode includes the option of automatically flipping the screen between turns for players sitting across from each other at a table, on the floor, in the car, or on a plane.

iFarkle is simple to learn and fun to play.
1994 - 1998

Bachelor of Science Degree in Computer Engineering

Rose-Hulman Institute of Technology - Terre Haute, Indiana

Libraries/APIs

Alamofire, Sockets, Codable, TrustKit, CocoaPods, Firebase iOS SDK, HealthKit, Twilio API, WebRTC

Tools

Xcode, TestFlight, Git, Subversion (SVN), Firebase Analytics, Twilio Programmable Video

Frameworks

Core Bluetooth, JSONModel, AFNetworking, iOS SDK, Core Data, Core Location, SwiftUI, EventKit, Address Book, UIKit

Languages

Swift, Objective-C, Java, PHP, C++

Paradigms

Agile, Scrum, REST, Mobile Development

Platforms

tvOS, MacOS, iOS, WatchOS, Mobile, Firebase, Android, Twilio, Bluetooth Low Energy (LE), OpenTok

Storage

MySQL, SQLite

Other

AVFoundation, Software Development, Cryptography, Encryption, Mobile Architecture, Async/Await, Architecture, EMV, Credit Cards, Contactless Payment, WebSockets

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.

1

Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring