Overview:
PayPal Checkout with Smart Payment Buttons gives your buyers a simplified and secure checkout experience. PayPal intelligently presents the most relevant payment types to your shoppers, automatically, making it easier for them to complete their purchase using methods like Pay with Venmo, PayPal Credit, credit card payments, iDEAL, Bancontact, Sofort, and other payment types.
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All the content above is take from the the PayPal Overview page here, https://developer.paypal.com/docs/checkout/.
Setup:
In order to configure PayPal Smart Payment Buttons we need you to create a “Straightsell” App in your PayPal account and provide us the Client ID and Secret for this new App.
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