This paper presents the design and implementation of <em>Land Guard</em>, an open-source enterprise GIS system developed to improve cadastral parcel map production and management in Iran. The research addresses the limitations of the existing TAM–Transpoly workflow, which relies on fragmented tools, lacks real-time validation, and depends on proprietary formats. Using a Design Science Research Methodology, the system was developed with Python, PyQGIS, PyQt, and PostgreSQL/PostGIS. Land Guard integrates spatial and descriptive data entry in a single interface, performs real-time topological and administrative boundary validation, and stores data directly in an enterprise spatial database with role-level access control. A usability evaluation with 10 surveyors showed a 50% reduction in workflow time and a 40% reduction in user interactions compared to Transpoly. While not fully LADM-compliant, the system’s conceptual schema is mapped to LADM schema. The findings demonstrate that free and open-source GIS technologies can deliver scalable, secure, and user-friendly cadastral systems, supporting digital transformation in land administration.