The design of urban green spaces is an essential part of urban planning and development. GIS-supported tools utilizing data-based indicators help to facilitate this process and identify deficits in the supply of urban green spaces (UGS). This paper introduces a comprehensive set of GIS-based indicators designed to assess the supply, demand, and accessibility of UGS within the framework of the planning instrument Geo Open Accessibility Tool 3.0 (GOAT 3.0). Recognizing the vital role of UGS for public health and the well-being of urban populations, the study focuses on the city of Munich, Germany, as a pilot region. The indicators, categorized into supply, accessibility, and supply-demand ratio, are implemented and tested, showcasing their applicability and relevance. Utilizing a hexagonal grid and routing-based methods, the indicators provide an objective depiction of UGS on various scales. The study contributes to digital landscape planning by bridging the gap between simple indicators and more complex, routing-based approaches. It highlights the need for high-quality data, particularly in relation to UGS and population, and suggests parameterizable accessibility indicators for planning purposes. The indicators presented provide a valuable tool for monitoring, planning, and managing UGS, with potential applicability to cities worldwide, where comparable data is available. The paper concludes by discussing future developments, including the refinement of indicators and the incorporation of additional parameters that describe the quality of UGS.