Adding the Express Checkout Button

You must show a Clearpay checkout button on your cart and/or product pages to enable Express Checkout. When clicked, the Clearpay checkout button will start the checkout process in a popup flow (the redirect flow can optionally be used with Deferred Shipping).

MySchoolBucks - Pay Express Buttons

Creating a Shareable Payment Link (Text Link or URL) - WP Express Checkout

paypal-express-checkout-smart-payment-buttons - Event Smart

PayPal - Intershop Communications AG

Express button

PayPal Express Checkout in PHP for Single Product

Checkout Methods: Standard and Express Checkout

magento 1.7 - How to enable PayPal Website Payments Standard & Express Checkout at the same time? - Magento Stack Exchange

How to hide / remove Express Checkout buttons in Shopify