Full-Stack Developer for Website and App

I'm looking for a skilled developer to create both a website and an app for iOS and Android.

Essential functionalities include:
- User login
- Payment integration
- Real-time notifications
- Location services
- GPS
- Time tracker

Ideal Skills and Experience:
- Proficiency in both web and mobile app development
- Experience with user authentication and payment gateways
- Knowledge of real-time data processing and notifications
- Familiarity with location services and GPS integration
- Strong background in time tracking application development

Please provide a portfolio with relevant projects.