[luizcdc]

Yes, the transactions is tripartite.

Direct API access to the Central Bank's internal system is only given to participating banks. Your bank might make available a separate API through which you can generate temporary QR Codes with a value attached, for instance. This is very common. These QR codes aren't requests for payment in the strictest sense, because they aren't targeted at an user specifically: anyone that scans the QR code can pay.

To popularize the system, the central bank forbid the banks from charging for transactions in the first 12 months. That was very contentious because before we had a system called TED which allowed transactions only in business days and within a 1~24h window. Most (not all) banks charged a fixed fee of 1 to 15 BRL per transaction. This revenue source was cut all of a sudden.

Now, they allow banks to charge fees for businesses, if they wish. Some banks have fixed fees, some charge up to 1% per transaction (half the fee for debit card transactions in Brazil), sometimes also defining a ceiling (max 130 BRL fee per single transaction).