On iOS, Apple Pay can be easily integrated both with and without our SDK. In both offerings, there will be the need for you to sign up for an Apple Developer account and create your own Apple merchant ID and processing certificate.

Using SDKWithout SDK
Apple Developer account required?YesYes
Apple merchant account required?YesYes
Customization & Theming?LimitedFull
Domain association required?NoNo
Integrated with Checkout Flow?YesOptional

Apple Pay is also available on the web.