Razorpay Integration for Firebase

My website is already live on Firebase Hosting; what’s missing is a smooth Razorpay checkout flow. I need payment gateway support that accepts Credit/Debit Cards, UPI, and Net Banking. The front-end is in place, so your focus will be wiring up Razorpay’s web SDK, generating the order on my backend (Cloud Functions), and handling success / failure callbacks to update Firestore.

Key deliverables
• Razorpay order creation endpoint in a Firebase Cloud Function
• Secure client-side checkout modal for the three payment methods above
• Proper success, failure, and cancel handling that updates the order document and shows the right UI message
• Brief README or inline comments so I can maintain keys and environment variables myself

The Razorpay account is not active and API keys are also not ready because i need to connect it to a custom domain so i need a little help in connecting domain to hosting too after that I’ll share them over a secure channel once we start. A clean, well-commented implementation that follows Razorpay’s best practices is all I’m after—no overhaul of existing code. i need all the work to be done through teamviewer or anydesk as i cant share all the credentials since its linked to one another