How to validate a UPI ID using regex?

Question

It's like an email ID but can start from a digit also and doesn't have a domain at the end.

Examples:

rishi.21@axis
shruti@PNB
98765__210@upi

Answer 1

Ideally there is a minimum number of characters before and after @. Hence following can be added for same:

[a-zA-Z0-9.\-_]{2,256}@[a-zA-Z]{2,64}