Currently, more than two billion people access the Web for various purposes. The majority are people without programming or modelling background. Part of these people(called end-users) also likes to create their own Web applications to meet their daily needs. Mashup Makers are tools to create such end-user's Web applications. As such, Mashup Makers could become the dominant environment for end-user development of Web applications. Existing Mashup Makers promise that creating a Web Mashup is very easy and just a matter of a few mouse clicks. However, there is no evidence that this is indeed the case. On the contrary, research has already revealed usability problems with Mashup Makers. Therefore, we target the achievement of a consolidated approach, model, and framework for the evaluation of the usability of Mashup Makers for end-users. Such a framework will not only allow evaluating the usability of existing Mashup Makers, but it will also provide key issues concerning usability(i.e. usability impact factors) that developers of Mashup Makers and of other future end-user development tools can take into consideration when developing new tools.