On-demand computing has transformed enterprise software, lowering risk and cost while increasing user adoption and customer success. To be successful, an application must be designed for on-demand from the ground-up, including core architectural elements such as multi-tenancy, availability, performance, security, metadata-driven customization, integration via web services, etc. As with any new paradigm, initial applications must design and implement all these core attributes, but ultimately platforms emerge that encapsulate core computing services, allowing application developers to focus on innovation and value, and not on reinventing the wheel. With AppExchange, salesforce.com has delivered the first ondemand platform, allowing developers to easily develop and deliver the next generation of on-demand applications. In this talk, Steve Fisher discusses the technical architecture of the AppExchange platform.