JsonLogic structures, based on JavaScript Object Notation (JSON), are used in software applications in order to create business process rules. However, JsonLogic’s textual syntax is different from the general purpose programming languages and it causes difficulties on the formalization of complex business rules. This unfamiliar way of rule creation may also lead to a time-consuming and error-prone development process. In this paper, we introduce a web based visual modeling tool which facilitates the construction of such business rules by following a model-driven engineering methodology. Inside this tool, the developers can visually design business rules with the block programming approach and corresponding JsonLogic codes are automatically generated. Moreover, changes made in these auto-generated codes can be reflected automatically to the related models inside the tool without any human intervention. Hence the synchronization between JsonLogic models and codes is provided. It has also been found that JsonLogic business rules can be created with significantly fewer visual components and hence with simpler models in comparison with the unique editor currently available for the similar purpose. The modeling tool is now used by Hermes Iletisim company during the development of various commercial software products.