A system and method for a web-based services architecture providing integrated modular building blocks for creating and maintaining a web site and related transaction processing to support electronic commerce and the sales of products and services using the web site. The transaction processing may include the handling of transactions and communications related to product and service sales and fulfillment involving customers, merchants and the web site owner. The services architecture may combine software front-end, back-end, and marketing tools to assist business owners to create or expand an Internet-based business. The services architecture also may provide a warehouse of predefined products that may be integrated into a merchant's existing online inventory.