Utopia is a SuperCollider library for the creation of networked music applications, and builds upon the work of the Republic Quark and other existing network systems in SuperCollider. It aims to be modular (features available largely 'à la carte'), secure (provides methods for authentication and encryption), and flexible (to the extent possible, it tries not to impose a particular design or architecture). It provides functionality for synchronisation, communication, code sharing, and data sharing.