Abstract: A system and method for shopping at a variety of different vendors easily and securely is disclosed. A user computer, a checkout processor, and one or more merchant computers are interconnected via a network. A user first selects a merchant and receives product information from the merchant. The user may select products from the merchant along with options for the selected items. When the user is finished shopping at a particular merchant, the user may select another merchant or checkout. At any time during the shopping or during checkout, the user may modify items previously selected by the user. When the user requests to checkout, product selection data is transferred to a secure central checkout processor and the checkout processor obtains order information from the user, performs review order processing, and then processes the order.