How do payment systems work?

Question

Payment systems

Most payment systems take a commission of approximately 3% of what passes through them. But there are also turnkey solutions on the market - it's like you put it on your server and accept payment without commission.
Let's imagine that I want to develop a payment system (no)
How does it work? API Wallet integration? And 54 FZ? What agreements are made for this?
There is very little information on the Internet about this.

Answer 1

turnkey solutions - sort of like you put it on your server and accept payment without commission.

you will still pay a commission to the bank that will serve you.
Now the simplest thing is to go to the bank or immediately to the NSPK with such a question, also read about PCIDSS and how much it costs.

Answer 2

These are fantasies. The key is here
I don't have any вроде как. The creation of a payment system is an investment of millions of dollars only in terms of relationships with banks (letters of credit, lines of credit, guarantees). I'm not talking about investments in the software creation of a safe product, its certification, marketing, and so on.