Hello sir.
I have rich experiences in shopping app dev.
I have developed payment app and merchant/customer marketing app dev.
I am very familiar with paypal and credit card, QR and bar code reader.
If you prefer me, i'll aid your business with integrity and give you the best result.
I can develop your app so much rapidly.
From my apps, please check if i am suitable for your work. followings are my answers to your asking.
Thanks.