iPhone apps
Native iOS apps in Swift and SwiftUI, designed for the platform and built to pass App Store review the first time.
SwiftSwiftUIiOS
Build: Mobile Development
MOBILE APPS, ON DEMAND.
Mobile is part of Build, the side of GMX3C that grew out of a passion for making apps. The same craft behind PulseAware and HeadPause is available on demand: iPhone, iPad, Apple Watch, and Android apps in Swift, Kotlin, or React Native, whichever fits, taken all the way through the App Store and Google Play.
What We Build
From the first screen to the store listing.
iPad apps
iPadOS apps built for the larger screen: split view and multitasking, Apple Pencil, keyboard and trackpad, and tablet layouts for in-store, kiosk, and field use.
iPadOSSwiftUIApple Pencil
Android apps
Native Android apps in Kotlin and Jetpack Compose, tested across devices and released through Google Play.
KotlinJetpack ComposeAndroid
Cross-platform apps
One codebase for iPhone and Android with React Native and Expo when speed to both stores matters more than platform-specific polish.
React NativeExpoTypeScript
Apple Watch and wearables
watchOS companions, HealthKit, and motion sensing for apps that live on the wrist or read the body.
watchOSHealthKitCore Motion
The backend behind the app
APIs, sign-in, push notifications, payments, content management, and analytics, so the app has everything it needs on day one.
APIsAuthPushPayments
Design and prototyping
Screen design, clickable prototypes, and a design system that feels native on iPhone, iPad, and Android before a line of production code.
UXUIPrototypes
Store launch and release
TestFlight and Play testing tracks, store listings, privacy disclosures, review submission, and repeatable releases.
TestFlightApp Store ConnectGoogle Play Console
The Right Stack
Built for the requirement, not the trend.
Native iOS
Swift and SwiftUI
The app is Apple-first, leans on the Watch, health data, or device sensors, or needs the most native feel.
Native Android
Kotlin and Jetpack Compose
The audience is Android-first or the app needs deep Android integration, hardware access, or enterprise device management.
Cross-platform
React Native and Expo
Both stores matter, the budget favors one codebase, and the experience is content, forms, ordering, or account driven.
Shipped by GMX3C
Apps live on the App Store today.
PulseAware
iPhone and Apple Watch
Real-time stress and speaking awareness from heart rate, HRV, and voice, with on-device processing.
HeadPause
iPhone with AirPods
Guided balance and stillness practice using AirPods head tracking. On-device and private by default.
How It Works
From idea to App Store in five steps.
01
Discovery
Goals, users, must-have features, and constraints, turned into a clear scope and the right stack.
02
Prototype
Clickable screens or a working build early, so decisions are made on something real.
03
Build
Short iterations with regular test builds on real devices through TestFlight and Play testing tracks.
04
Launch
Store listings, privacy details, review submission, and release to the App Store and Google Play.
05
Support
Updates, OS compatibility, fixes, and new features as needed, on demand rather than on retainer.
Have an app in mind?
Tell us what it needs to do. We will recommend the right platform and stack, and scope it with you.