NET ZONE Pay

Enter amount → make QR → customer scans and pays
UPI QR
Scan with any UPI app (GPay / PhonePe / Paytm)
Payment link (made with the QR above) - send it to the customer; their phone tries to open their UPI app:
Everything stays in this browser - nothing is uploaded. Some UPI apps may not show the amount; the customer then enters it themselves.