ENTIRETY is an open-source web application that provides consistency for the devices in IoT platforms with a simple and unified way of governing and provisioning. This service primarily targets smart energy domain applications in a large-scale scenario but can be easily extended to support other domain-specific devices. To overcome the IoT diversity challenges, the core of the ENTIRETY is a SARGON ontology which is the semantic data model designed for cross-cutting the domain-specific information in the smart energy system which is modular, extendable and reusable. Consequently, ENTIRETY is intended on underlying principles such as reusability and extensibility, it applies a template-based approach and can be run as a Docker image.