Cross-Platform E-commerce App Development

I'm looking for an experienced app developer to create an e-commerce application that works on both iOS and Android platforms.

Key requirements:
- User-friendly interface and seamless navigation
- Secure payment gateway integration
- Robust backend to manage products, orders, and users
- High-level security features to protect user data

Ideal Skills and Experience:
- Proven experience in developing cross-platform apps
- Strong knowledge of e-commerce functionalities
- Expertise in UI/UX design
- Proficient in backend development and database management
- Familiarity with security protocols and data protection

Please provide a portfolio showcasing similar projects.