Until now, when paying for an online purchase, merchants had to contact a series of intermediaries who, in turn, connected to the company responsible for the card (e.g. Visa or MasterCard) to finally debit a current account. With PSD2, however, the consumer will be able to authorise the merchant to execute payments on his behalf via his bank account. Thus, the merchant and the bank will now communicate via the mobile phone with an API (application programming interface). The API ensures the protection of the user's bank details through a strong authentication system (SCA) that aims to prevent fraudulent transactions.