As more educational activities are conducted online, the need for interactive applications (apps) that can effectively support educators in their practice is increasing. These apps are often created by web developers or by researchers, educators, and even students with programming experience. While a large body of work has focused on incorporating these apps into educational contexts, fewer studies have focused on their development. In this paper, we first present the design and implementation of an app development framework aimed at supporting developers in creating apps for education. We then report the results of a study comprising interviews with 12 developers who used the framework. Our findings highlight that while the creation of web apps for education can be facilitated by a purely software-based app development framework, effectively exploiting such a framework requires domain knowledge that could be acquired through in-depth documentation, tutorials, and collaboration between developers and educators.