Billing system with a convenient api?

Question

Payment systems

Hello.
A service is being developed where some users will be able to sell digital content to others
. What payment systems allow making payments via api?
That is, with a regular store, everything is simple, there is a robocasa or an analogue that allows the client to buy goods and transfer money to a specific account.
Interested in a system that will allow you to make payments within seller users.
Thank you in advance

Answer 1

Here for this
This
is the heart of the system.
It is rather strange to use external billing for such purposes.
When money is withdrawn from the system, you can use all the same payment systems as usual.