The Normalized Principal Moment of Inertia ratios (NPR) plot is a method for characterizing the shapes of molecules based on their rotational motion. Two studies, CD44 antagonist candidates for tetrahydroisoquinoline-based molecules and protein pocket shape comparison in virtual screening, show how important NPR can be in drug discovery . This web-app's shape analysis module employs the RDKit Descriptors3D module to compute NPR 1 and NPR 2 , which describe the molecular shape for each molecule in both datasets based on ratios of the principal moments of inertia of a molecule