Cross-Platform Business App Development

I need a skilled developer to create a mobile business application for both iOS and Android platforms.

Essential Features:
- User authentication
- Payment processing
- In-app messaging

Ideal skills and experience:
- Strong proficiency in mobile app development for iOS and Android
- Experience with user authentication and payment processing integrations
- Background in implementing in-app messaging systems
- UI/UX design skills are a plus

Please provide your portfolio and relevant experience.