Experience
Kairis | kairis.app
The Hague, NL
Creator / Developer
Designed, architected, and shipped a SwiftUI iPhone app to the App Store (Health & Fitness) as sole developer; ~40,000 lines of Swift
- Architected a SwiftUI/MVVM application with Swift Concurrency and SwiftData for on-device persistence, enforcing a privacy-first, zero-telemetry design.
- Modularized the codebase via Swift Package Manager, extracting a local engine package to decouple domain logic (circadian modeling, scheduling, audio orchestration) from presentation.
- Implemented the cosinor model for parametric circadian rhythm projections exposing normalized physiological parameters as continuous functions of time, driving custom interactive SwiftUI visualizations and a WidgetKit widget suite.
- Engineered a real-time multi-track audio engine on AVAudioEngine, composing multiple AVAudioPlayerNodes through AVAudioMixing graphs with custom scheduling to layer voice, music, ambient soundscapes, binaural beats, and effects into synchronized guided sessions.
- Built a procedural audio cue generator that composes chromatic tone sequences into musically coherent scales and chords, parameterized by user-calibrated breath durations.
- Developed a custom animation controller synchronizing SwiftUI animations, TimelineView-driven shape rendering, and audio playback; built a guided breath-calibration wizard deriving personalized exercise parameters from measured user input.
- Integrated WeatherKit and CoreLocation for real-time environmental signals (solar events, lunar phase, UV, temperature) across the visualizer and widgets.
- Implemented a configurable protocols/scheduling system with full recurrence and UserNotifications-driven local reminders tied to the user's circadian timeline.
- Integrated Apple Intelligence and the Foundation Models framework for on-device adaptive journaling prompts, with graceful fallback on unsupported hardware.
- Implemented a freemium monetization layer with StoreKit and exposed core actions via App Intents.
- Designed a multi-metric self-tracking module with daily goals, streak logic, and hour/week navigation, instrumented automatically by in-app sessions to reduce manual entry.
- Established Swift Testing coverage on the engine package's deterministic domain logic; profiled and optimized CPU, memory, and latency using Instruments.
- Owned full product lifecycle solo: architecture, UX, audio production, graphic design, App Store submission, release management, and post-launch iterations.
- More information at [ kairis.app ]
JANUARY 2025 - PRESENT
Amazon
San Francisco, CA | The Hague, NL
Senior engineer on distributed teams bridging client applications with backend services across multiple problem domains; technical lead on client-facing features and cross-platform infrastructure.
- Served as tech lead for small teams (3–5 engineers plus PM and TPM), driving up to two concurrent projects from design through launch and coordinating across partner teams.
- Owned and delivered multiple high-traffic surfaces of the Amazon Music iOS app — album/artist/playlist pages, portions of the home screen, browse, library, the free tier, and the offline/download subsystem.
- Developed across a predominantly native Objective-C/Swift codebase with React Native surfaces, spanning feature work, framework design, and shared client libraries.
- Contributed full-stack backend services in Java, Kotlin, and Node/TypeScript, integrated with the broader Amazon Music service ecosystem via Coral, Apollo, Brazil, and internal deployment pipelines.
- Built backend components on AWS primitives including Lambda, DynamoDB, S3, SQS, SNS, API Gateway, CloudFront, Cognito, IAM, CloudWatch, and Route 53.
- Authored and reviewed design and technical evaluation documents, setting direction and raising the engineering bar across feature and architecture decisions.
- Led project planning and resource allocation, balancing delivery timelines against operational and technical constraints across multiple workstreams.
- Designed and built an internal cross-platform analytics SDK using Kotlin Multiplatform, targeting iOS, Android, and React Native consumers to unify instrumentation across first-party clients.
- Owned monitoring and operations for delivered systems, including on-call response, observability, and post-launch reliability.
- Mentored and grew junior engineers through coaching, design feedback, and structured technical guidance.
- Participated extensively in interviewing and hiring, conducting well over a hundred interview loops to help raise the team's hiring bar.
JULY 2019 - MARCH 2024
eBay, Inc
San Francisco, CA | Portland, OR
Member of Technical Staff (MTS2) responsible for various areas of the selling flow on the eBay iOS app.
- Tech lead on pre/post-selling portion of the iOS app
- Development of iOS applications using Objective-C & Swift
- Agile team lead
- Coaching & growth of junior engineers
- Code review & management
MARCH 2016 - MARCH 2019
CBS Interactive (née CNET Networks)
San Francisco, CA
Software Engineer (Associate through Principal) & Engineering Manager on CNET, ZDNet and other CBS web & mobile properties. I kickstarted the mobile Development at CNET and delivered its first iOS app, which reached #1 on the Apple App Store (News category).
- Tech lead & people manager of a team distributed across 3 different locales (SF, KY, UK)
- Created CNET Reviews iPhone App featuring product reviews, comparisons, search, buying guides.
- Designed & implemented the original iPhone version of CNET (iphone.cnet.com)
- Authored CiUI – an open-source web-based framework to mimic native iPhone UI
- Developed iOS applications using Objective-C & Swift
- Owned and was responsible for several key, high-revenue front-end and back-end applications on reviews.cnet.com and news.cnet.com using Java/ Spring/Hibernate and various scripting languages
- Won CBSi Impact Award for outstanding contribution to the organization
- Won Hack Day award, a 24-hour coding competition
- Won "Superman" award by completing voice-powered natural language search app and a mobile learning framework in 24 hours
- Won MVP title in an internal prototyping competition
FEBRUARY 2007 - MARCH 2016
Cohen & Grigsby, P. C.
Pittsburgh, PA
Software Engineer responsible for development of internal applications for medium-sized company. I worked with the CTO and the director of engineering to deliver Lotus Domino and other web apps to our internal customers.
- Develop PHP, Visual C++, VB, Lotus Domino applications in Linux, BSD (Darwin) Apache and IIS Web Server environments
- Provide technical assistance with client and server administration tasks
- Provide quality assurance and debugging of various applications
JANUARY 2004 - FEBRUARY 2007
Five Star Development
Pittsburgh, PA
Web Developer in a small web development company working on training modules for 3rd party clients.
- Program web applications following design specifications and technical leader instructions using .NET technologies
- Provide debugging, quality assurance, and documentation of developed applications
- Work as a part of a team to develop creative and technical approaches
- Communicate status, issues, roadblocks, and ideas
MAY 2003 - JANUARY 2004