NodeJS Backend for User Management App

I'm seeking an experienced NodeJS developer to build a robust backend for a user data management application. The frontend web dashboard is already developed, and the database will be Firebase.

Essential Features:
- User authentication and authorization
- User profile management
- Activity logging
- User transactions
- Managing user sub-user details
- Role-based access control with multiple roles and permissions

Payment Gateway:
- Integration with PayFast

Ideal Skills and Experience:
- Proficiency in NodeJS
- Experience with Firebase
- Strong background in implementing payment gateways, especially PayFast
- Knowledge of role-based access control
- Familiarity with user data management systems

Please provide examples of similar projects you've completed. Looking forward to your bids!