Custom Mobile Wallet that works Offline


I would like to develop a mobile application allowing to make payments in a store by scanning the QR Code or by using a user code.

The challenge :

  • Run the app offline
  • It should allow payment in every country
  • Minimize costs (free SDK/API for example if it exists)

What will I need?

  • Will it be necessary to use a solution like Stripe for example? An API? An SDK?

I really need your help please

I don’t think you can do something purely offline unless it’s just holding the equivalent of credit card info like Apple Wallet and similar do. You need some sort of connection with wherever the money is being held to verify and initiate the transfer.

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Okay, let’s say a device in the store is connected so that the Customer’s phone can send data to it via QR Code.

  • Will it be possible? Or QR Code will also need internet

If it’s not possible online, then how to do it online? I have seen so many SDKs, APIs… I’m lost.
I don’t think I can build something from scratch.

  • So, what do I need?

You cannot have an offline method of paying because your money needs “credentials”. AKA the shop wants to be sure they actually get the money.

This is done via an internet connection to whatever service holds your money - an API. Be it your bank or some inbetween service like PayPal.

That could work, if you find a service that would allow this.
The problem is… well at that point the phone basically doubles as a card for your bank account. Those cards also have no internet connection but hold some personal information and credentials which a card-reader can read out and use to connect to whatever financial-service-API is behind that.

The problem is, you cannot build that yourself. You have to rely on whatever API the financial institute offers. And even worse, they might not openly give out information for that because making to much of the API public could invite scammers. Because not only the store wants it’s money after the transaction - but I also want the bank to protect my money so no scammer can just trick the API to think s/he is actually me.

I mean, a service like PayPal protect my account with my password. So maybe I’m overselling the security in general (although PayPal most likely has safety measures in the back, checking for unusual transactions).


Thank you all for your replies. I’ll try to figure out a solution.

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