Merchant Fulfillment API Section - Version 2015-06-01
With the Merchant Fulfillment service, you can build applications that let sellers purchase shipping using Amazon's Buy Shipping Services. Your applications can:
Purchase shipping labels and confirm shipments for all Amazon orders. Get access to Amazon's negotiated seller rates across major carriers to purchase shipping.
Pay for shipping and related services using the seller's Amazon account.
Prepare for Seller Fulfilled Prime. Shipping for all Prime products must be purchased through Buy Shipping Services.
In addition, your applications can provide the following benefits to sellers in the US:
Purchasing shipping labels from UPS and FedEx at discounted rates. All domestic USPS shipping can be purchased at USPS Commercial Plus prices.
Preventing A-to-z Guarantee claims. If an order is shipped with tracking using Buy Shipping Services, and the buyer files a claim stating they did not receive the order, Amazon will cover the A-to-z Guarantee claim and the seller’s Order Defect Rate will not be affected.