Native where it counts
Swift and Kotlin when the app needs true 120fps scrolling, deep OS integrations, or hardware access — React Native and Flutter when speed to store wins.
Status: booking one new app project for next quarter — get on the calendar
iOS & Android engineer · Seoul
I ship mobile apps people keep
Native and cross-platform apps built to feel fast on the first launch and stay smooth after the thousandth. Browse the work, then tell me what you want on the store.
How I work
What a launch with me looks like
Ten years of shipping to the App Store and Google Play taught me where mobile projects usually stall. Here is how I keep them moving.
Offline-first by default
Phones lose signal in elevators and subways. I build a local-first data layer with conflict resolution so the app never shows a spinner it can't finish.
Reviews you can measure
Cold-start time, crash-free rate, and store rating are the metrics I chase — every case study below lists the number, not just the tools.
Shipped apps
Projects
A handful of apps that made it to the store. Tap any card for the role, the stack, and what shipping it changed.
FeaturedLumen — Meditation & Sleep
2024A calm iOS app with spatial-audio soundscapes, offline sessions, and a Live Activity that follows your breath.
SwiftSwiftUIAVFoundationHealthKit
View case study 
FeaturedTrailMark — Offline Hiking GPS
2023An Android app that records hikes with GPS breadcrumbs and works with zero signal deep in the mountains.
KotlinJetpack ComposeRoomGoogle Maps SDK
View case study 
Ledger — Team Expenses
2023A cross-platform expense app with instant receipt scanning and real-time team budgets on iOS and Android.
React NativeTypeScriptFirebaseVision Camera
View case study 
Pulse — Fitness Companion
2022A Flutter app that mirrors live workout metrics from a Wear OS and watchOS companion in real time.
FlutterDartIsarwatchOS
View case study 
FeaturedNara — Mobile Banking
2024A native banking app rebuilt in SwiftUI and Jetpack Compose, with biometric login and a sub-second cold start.
SwiftSwiftUIKotlinJetpack Compose
View case study Have an app in mind?
Whether it's a fresh launch or an existing app that needs to feel faster, I'd love to hear about it. Let's scope it together.