From 30 May, New Zealand's four major banks - ANZ, ASB, BNZ and Westpac - must offer the secure payment service - although some already have it in place.

It allows customers to give a third party (such as an online retailer) permission to connect to their banking information, meaning there is no need to enter credit or debit card details to make a purchase.

Open banking can be used both on retailers' websites and on their mobile app, if they have one