Free Fire Diamond Top-Up Site

I need a developer to create a Free Fire diamond top-up site and control the site via mobile.

Essential requirements:
- Payment gateway integration is critical
- Support for mobile payments and UPI
- Mobile-friendly interface for site management
- Site should be in English only

Ideal skills and experience:
- Experience in developing e-commerce or top-up sites
- Strong background in payment gateway integration, especially with mobile payments and UPI
- Proficiency in mobile-responsive design and development
- Knowledge of user account management systems

Please provide examples of similar work done.