Flutter App Development with Backend with API

I'm seeking a skilled Flutter developer to create a multi-platform app (iOS and Android). The app will require a robust backend and API integration.

Key Features:
- User authentication
- Push notifications
- Payment gateway integration

Ideal candidates should have:
- Proficiency in Flutter
- Experience with backend development
- Strong knowledge in API integration
- Familiarity with user authentication and payment systems

Please provide examples of similar projects you've completed.