Koen Vestjens

Koen Vestjens

iOS Developer

iOS developer with 7+ years of experience building and shipping apps in Swift and SwiftUI. Worked on apps used by millions, from architecture to App Store release. Also experienced with Flutter for cross-platform projects.

Netherlands · · · Yellowcone Productions
Experience
iOS & Mobile Developer
Vanilla B.V. · Eindhoven, Netherlands (Remote) · Connecting 3M+ users worldwide
Nov 2021 – May 2026
  • Built a fully native iOS app in SwiftUI with HealthKit integration, custom animations, and accessibility support.
  • Used MVVM, Core Data, and Apple frameworks like HealthKit and StoreKit across projects.
  • Worked with designers and product owners on feature specs, did code reviews, and helped define coding standards for the mobile team.
  • Built multiple Flutter apps for iOS and Android, used by millions of people.
  • Handled the full App Store release process for multiple apps: provisioning, TestFlight, metadata, and phased rollouts.
Mobile App Developer
Oddessey Solutions B.V. · Eindhoven, Netherlands
Oct 2018 – Nov 2021
  • Built and maintained native iOS apps in Swift, with a focus on solid UX, networking, and local data storage.
  • Worked on React Native projects, writing native iOS modules when needed.
Team Leader
Supermarkt Heerschap Heythuysen B.V. (Jumbo) · Heythuysen, Netherlands
May 2009 – Jun 2019
  • Managed a team of 15-20 people: planning, scheduling, and day-to-day coordination.
Skills
iOS
Swift SwiftUI UIKit Core Data
Apple
HealthKit StoreKit WidgetKit UserNotifications
Cross-platform
Flutter Dart React Native
Back-end
TypeScript Firebase REST APIs
Tools
Xcode Instruments App Store Connect TestFlight Figma Git
Languages
Dutch - Native English - B2
Personal Projects
NamaBaby
Solo Project
Ongoing
Education
Bachelor's in Software Engineering
Fontys University of Applied Sciences, Eindhoven
2014 – 2018
MBO Diploma in Multimedia Development
Sint Lucas, Eindhoven
2009 – 2013