Optimization of software architectures is a complex task that can not be fully automated. For this reason, software architecture optimization approaches often require human architects to participate in the optimization process, e.g., by selecting architectural candidates. Nevertheless, most of these approaches fail to support architects in solving their tasks as they provide no or insufficient visualization and interaction techniques. Thus, architects usually have to invest time and effort to find a (not ideal) solution themselves. In this paper, we present SQuAT-Vis - a tool that can be plugged into software architecture optimization approaches and allows architects to investigate (intermediate) results visually. SQuAT-Vis has been developed based on four common use cases in the domain and to be compatible with the technologies used by SQuAT, which is a state-of-the-art software architecture optimization approach. Nevertheless, SQuAT-Vis is conceptually intended to be modular and compatible with other approaches as well. Such a tool is, therefore, an important contribution to the domain of (interactive) software architecture optimization.