I'm new on PayPal SDK, and have to integrate a payment gateway; I use PHP, and reading the documentation about the PayPal PHP SDK on GitHub says that the Merchant SDK is deprecated, in order to use the new Rest API SDK.
But, my question is: In Rest API SDK there is not any reference to Express Checkout, it have Payment Flow. So, ExpressCheckout is deprecated?
Sorry if I'm loss about this.
The Merchant SDK is deprecated; however, Express Checkout is not. The PayPal payment of the REST API leverages Express Checkout.
Edit: The deprecation note has been removed from the Merchant SDKs.
to be concise PayPal Express Checkout is called 'PayPal Payment' when using REST APIs. Please go here for REST API for a PayPal Payment and Here is a Reference Guide as well. Hope this helps!