Every organization needs a viable business model. Strikingly, most of current literature is focused on business model design only, whereas there is almost no attention for business model validation and actual implementation of and experimentation with business models. The goal of the research as described in this paper is to develop a business model engineering tool supporting business model management as a continuous design, validation and implementation cycle. The tool is applied to an online investment research startup with a scalable business model in roll out and market phase. This paper describes the research as performed in a case study setting by focusing on the design, implementation and evaluation of the business model engineering tool. We also analyze the actual implementation and usage of the business model tool by the online investment research startup by focusing on the most critical actions related to actual business model implementation & experimentation – i.e. actions with so-called ‘lollapalooza tendencies’.