FinTech Mobile Wallet

Client: PayFlow Inc. Industry: Financial Technology Duration: 5 months
FlutterDartFirebaseStripe ConnectNode.jsCloud Functions

The Challenge

PayFlow Inc. had a successful web-based payment platform but was losing market share to competitors with polished mobile experiences. Their existing React Native prototype suffered from sluggish animations, inconsistent behavior across iOS and Android, and security audit failures that blocked their PCI DSS compliance certification.

They needed a production-grade mobile wallet app that felt truly native on both platforms, passed rigorous security review, and could launch within five months to meet a partnership deadline with a major retail chain.

Our Approach

We chose Flutter for its ability to deliver native-quality UI with a single codebase while meeting the tight timeline. The architecture separated concerns into a clean layer structure: presentation (Flutter widgets with BLoC state management), domain (pure Dart business logic), and data (repository pattern wrapping Firebase and Stripe APIs).

Security was embedded from day one. Biometric authentication via platform-native APIs protected app access. All sensitive data was encrypted at rest using Flutter Secure Storage, and payment tokenization through Stripe Connect ensured card details never touched our servers. We worked directly with PayFlow’s compliance team to pass PCI DSS Level 1 audit on the first attempt.

The backend consisted of Firebase Authentication for user management, Cloud Firestore for real-time transaction feeds, and Node.js Cloud Functions handling webhook processing, fraud scoring, and push notification dispatch. We implemented comprehensive E2E testing with integration test suites running on both iOS simulators and physical Android devices in CI.

Results

  • 4.8-star rating on both App Store and Google Play within the first month
  • PCI DSS Level 1 compliance achieved on the first audit attempt
  • < 300ms average transaction processing time for peer-to-peer transfers
  • 60,000 downloads in the first 90 days of launch
  • 50ms frame render budget maintained across all animations (zero jank)