The development of Web-based modeling tools leverages Web technologies and Model-Driven Engineering (MDE) techniques to provide environments to create and edit models or model-based low-code solutions. These tools require providing a fast and efficient way for model management, which is especially important in model-based system engineering. However, there are still few approaches that provide this kind of model management. Among the strategies for developing distributed services, there is a growing interest in the use of RESTful services, as they allow providing stateless and scalable solutions. In this paper, we present a tool to provide RESTful services for model management that can be used to interact with any kind of model, and can be used to build a Web-based modeling tool providing modeling-as-a-service. We implemented the approach as a middleware, which is used to provision RESTful services for model management, and we evaluated the approach with a scenario-based methodology applied to the running example.