We introduce Kynoid, a real-time monitoring and enforcement framework for Android. Kynoid is based on user-defined security policies which are defined for data-items. This allows users to define temporal, spatial, and destination constraints which have to hold for single items. We introduce an innovative approach to allow for the real-time tracking and enforcement of such policies. In this way, Kynoid is the first extension of Android which enables the sharing of resources while respecting individual security policies for the data-items stored in these resources. We outline Kynoid’s architecture, present its operation and discuss it in terms of applicability, performance, and usability. By providing a proof-of-concept implementation we further show the feasibility of our framework.