title: Customize Shopify by integrating with a 3rd party gift card API
body: <p>We are looking to integrate Shopify with a 3rd party gift card service.  We want users to be able to buy a gift card provided by the 3rd party, and then when checking out on Shopify, to be able to use that gift card to pay for the purchase.</p>
  
  <p>The 3rd party gift card has APIs we can use.</p>
  
  <p>How could we do this with Shopify?</p>