Merchants using it will be able to put the Prime badge on their own websites beside eligible items available for free next-day or two-day delivery. Then, Prime members can purchase the product using the payment and shipping details already stored on their Amazon accounts.
Sellers will pay for the service with fees depending on the card processor, fulfillment and more. To start with, it's launching by invitation to Amazon sellers already using Fulfillment by Amazon (FBA), but will eventually expand to other merchants, even if they're not on Amazon.