- SPI: responsible for the payments

- DICT: responsible for mapping keys to accounts

The API documentation of those services are available, but only banks can use them. When a person wants to send money to another, there's an option in the bank app for sending through Pix.

Then you have many options to define to whom you'll send that money:

- typing the bank account information

- using the Pix key (which can be an phone, email, CPF/CNPJ (brazillian documents) or a generated key)

- scanning a QR code

Note that the two latter options don't require the account information. That resolution is done by DICT.

After that, you type how much you'll send (sometimes the QR code already contains this information). Then it'll send through SPI.

And yeah, it's really, really fast.