Cross-Platform Mobile App Development

I'm looking for an experienced developer to build a mobile application for both iOS and Android platforms. The app must include secure and seamless credit/debit card payment integration.

Key requirements:
- Mobile application development expertise
- Experience with both iOS and Android platforms
- Secure credit/debit card payment integration
- User-friendly interface
- Experience with back-end development

Ideal skills and experience:
- Proven track record in mobile app development
- Strong knowledge of payment gateways and security
- UI/UX design experience
- Familiarity with relevant programming languages and frameworks

Please provide examples of previous work and a detailed plan for the project.