Online social networks (OSNs) are immensely popular, but participants are increasingly uneasy with centralized services’ handling of user data. Decentralized OSNs offer the potential to address user’s anxiety while also enhancing the features and scalability offered by existing, centralized services. In this paper, we present Confidant, a decentralized OSN designed to support a scalable application framework for OSN data without compromising users’ privacy. Confidant replicates a user’s data on servers controlled by her friends. Because data is stored on trusted servers, Confidant allows application code to run directly on these storage servers. To manage access-control policies under weakly-consistent replication, Confidant eliminates write conflicts through a lightweight cloud-based state manager and through a simple mechanism for updating the bindings between access policies and replicated data.