We provide an analysis of third-party sellers on Amazon’s online marketplace from a customer’s viewpoint. While Amazon as a retailer sometimes directly competes with third-party sellers, Amazon is also interested in making the Amazon marketplace attractive for third-party sellers and making third-party sellers attractive to customers. Based on a large-scale survey (n=772) of Amazon customers in the U.S., we examine how much they like to buy from the different seller types (Amazon itself, third-party sellers with/without the Prime logo, i.e., with/without Fulfillment by Amazon). Among other results, we can show that the Prime logo on the seller side combined with a Prime subscription on the customer side significantly increases trust in a third-party seller, ultimately increasing third-party sales on Amazon’s online marketplace. Furthermore, third-party sellers are implicitly incentivized to use the Fulfillment by Amazon service, which generates additional logistics service revenue for Amazon.