So called "apps" are widespread today on the Internet. Most of them allow users to extend the range of functionalities their websites offer. However, they potentially jeopardize the privacy of users. Indeed, they collect, store and process personal pieces of information. Recent studies show that users feel they lack control over information. They also show that users distrust apps providers and would rather turn to their friends or family when they choose apps. In this paper we propose a model-driven approach to empower end-users with an extended control over their information. Our work is implemented as a web-based tool to compose apps and manage end-users privacy requirements. Our work showcases the unexploited possibilities of current web protocols and technologies in terms of privacy management.