This paper is aimed at presenting a concept of a flexible diagramming framework for building engineering and educational applications. The framework was designed to serve as a platform for online services and collaborative environments where users typically work on remotely stored, shared data through a browser-based user interface. The paper summarizes the common requirements towards such services, overviews related approaches and gives insights into some design challenges through the analysis of use-cases. The design problem is examined from a user-centered view: the key motivation of our research is to find innovative, possibly device-independent solutions that enable seamless user experiences. Finally a generic framework based on a HTML-JavaScript library is proposed, which could be employed for implementing wide range of software solutions from e-learning to cloud-based modeling environments.