TopologicPy is an open-source Python software library that supports rigorous 3D digital modelling, conceptual design, spatial reasoning, building performance analysis, and advanced applications such as graph-based machine learning. By using graph representations, TopologicPy helps architects create intelligent and analytically rich design models and to reason about spatial relationships, semantic information, and design intent from the earliest stages. It achieves this by carefully integrating geometry, topology, and semantics—an approach termed “syntopic”. This paper outlines the theoretical underpinnings of TopologicPy, describes its methodological implementation, and provides conceptual examples that illustrate its potential in architectural design and analysis through spatial reasoning, graph theory, and graph-based machine learning (GML).