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E-Commerce ON AG · 2024

Mobile-first Relaunch with Flutter

4.8★ App Store Rating

Company ON AG
Role Lead Mobile Developer
Expertise Flutter, CI/CD, E-Commerce

Starting Point

ON AG wanted to replace their existing web app with a native mobile app to improve the shopping experience and increase conversion rates. The existing solution was slow, had no offline capability, and lacked native look & feel.

4.8★ App Store
120k Downloads
4 mo. Timeline
99.5% Uptime

Challenge

The biggest challenge was integrating with the existing backend and payment infrastructure. At the same time, the app had to ship within 4 months — including CI/CD pipeline and automated tests.

!
The existing API wasn't optimized for mobile clients — we had to build a BFF layer (Backend for Frontend) to reduce latency and payload size.

Solution

We chose Flutter as the cross-platform framework to cover iOS and Android with a single codebase. The architecture is based on feature modules with clean dependency injection.

Performance Comparison
MetricBefore (Web)After (App)
Cold Start3.2s0.8s
Bundle Size1.2 MB420 KB
Offline SupportNoYes
Push NotificationsNoYes

Tech Stack

FlutterDartFirebaseFastlaneGitHub ActionsStripeGraphQL
App Screenshots — Home & Product Detail

Result

The app launched on schedule and reached over 120,000 downloads within 3 months. The App Store rating remains steady at 4.8 stars.

The app exceeded our expectations — both in quality and speed of delivery.

— CTO, ON AG

FAQ

Why Flutter instead of Native?

Flutter enables a single codebase for iOS and Android with native performance. This saves 40-60% of development time without compromising UX.

How long did the project take?

From kickoff to App Store launch took 4 months — including CI/CD pipeline, automated tests, and beta phase.

How was the API integration solved?

We built a BFF layer (Backend for Frontend) that translates the existing REST API into optimized GraphQL queries.

KH
Khalit Hartmann Freelance Mobile & Full-Stack Developer