Cross-Platform E-commerce App Development

I'm looking for experienced e-commerce mobile application developers to build a comprehensive app for both iOS and Android platforms using Flutter.

Core Features Required:
- Payment Gateway Integration
- Product Catalog
- User Authentication
- Notifications

Ideal Skills and Experience:
- Expertise in Flutter development
- Proven track record in building e-commerce mobile applications
- Strong understanding of payment gateway APIs
- Experience with user authentication processes
- Ability to implement notification systems

Please provide a portfolio showcasing relevant projects.