This paper proposes an IPv6-based network service control architecture for providing a variety of customized services to both stationary and mobile users in a unified manner. Recent trends in the Internet indicate its evolution into a combination of broadband and mobile-aware networks. One means of providing users with cost-efficient customized services in such large-scale IP networks is to introduce flexible network intelligence capabilities for managing network resources and services. The purpose of the proposed network architecture is to upgrade the Internet so that it functions more intelligently by using service profiles (data sets containing the service specifications of individual users) and mechanisms for their distribution. It is possible to make network services intelligent by using network application programming interfaces (APIs), which have been under study in international standardization groups. We apply the open API concept to our proposed architecture to produce a wide variety of services. We also propose a new open API to support Web content adaptation services, which add value to Web access.