Seattle—Amazon.com Inc. has introduced a service that allows customers to make purchases with third-party e-commerce businesses using their existing Amazon login information. Called Login and Pay with Amazon, the service—a direct competitor to PayPal—is intended to streamline the registration, log-in and payment process for online vendors. The service includes processes already familiar to Amazon.com customers, including managing and tracking orders, purchase history detail, special discounts and access to shipping addresses and payment methods, the company said in a statement. Participating sites will have access to customer names, email addresses and postal codes, allowing them to market to customers directly. The new service is priced at 2.9% of the price of each purchase, plus a 30-cent transaction fee for purchases of $10 or more, the company said.