Balancing the requirements of urban planning with the need for rapid and efficient iterative design, while accurately assessing its detailed impact on existing surrounding buildings at a per-room level, presents a significant challenge in architecture design, the conversion and integration between multiple platforms introduce additional complexity, establishing high standards for designers to achieve. Integrating Building Information Modeling (BIM), Geographic Information Systems (GIS), and per-room daylight simulation into a unified workflow offers a promising solution. This thesis develops a web application that leverages Grasshopper(GH) scripts for backend processes, Rhino Compute as the intermediary API, andMapboxGL as the GIS-based front-end platform, enabling seamless user interaction with BIM data for customized daylight simulations.Since the advent of digital tools, architects have sought ways to enhance and streamline the design process. Integrating these technologies bridges the gap between urban planning and indoor daylight simulation, facilitating real-time interaction and data manipulation. Grasshopper scripts are developed to compute Aperture-BasedDaylight Modeling (ABDM) metrics, Sunlight Beam Index (SBI), and sky lumen, providing a foundation for evaluating their relationships with traditional Daylight Modeling (CBDM) metrics like Daylight Autonomy (DA), Spatial Daylight Autonomy (sDA), and Useful Daylight Illuminance (UDI).This research explores the potential of combining these advanced tools to create an interactive web application that allows users to manipulate building typology, location, scale,façade materials, and levels of detail (LOD) for surrounding city models. The study demonstrates a robust linear relationship between SBI and the daylight metrics DA, sDA, and UDI, with room geometry playing a crucial role. Skylumens, however, show limited effectiveness as a CBDM alternative.The thesis concludes that MapboxGL is a promising platform for integrating BIM models into room-based daylight simulations, offering an intuitive user interface for urban planners and designers. Rhino Compute technology ensures smooth data transfer and interaction, significantly enhancing the workflow. The study results show that SBI has a linear relationship with traditional CBDM metrics. However, multiple moderating variables affect this relationship, and it does not apply to north-facing rooms. Thus, SBI is not a current substitute for traditional CBDM metrics. Overall, this thesis provides a comprehensive framework for integrating BIM, GIS, and daylight simulation into a cohesive system, paving the way for more efficient urban planning and design practices.