build me an app -- 2

I would like to develop an E-wallet app. This app needs to be able to facilitate payments (both making and receiving). people using the app need to have the choice of either making a customer account, a merchant account, or both. I have already undergone the process of acquiring a merchant account from my financial institution, what I need this app to be is a payment gateway. This app also needs to be a hybrid app (both Android and iOS). Further details will be provided upon request.