@osarch @ericbuijs @normand Good question #SolveSpace has own integrated NURBS geometric kernel, that is dramatically smaller than Open CASCADE Technology (OCCT), but has limited features support as for now.

#libslvs is a SolveSpace own integrated geometry constraints solver, which already has a Python wrapper, used in Blender, FreeCAD, Pyslvs: https://github.com/solvespace/solvespace/issues/292

JFTR, There are some other apps with own CAD-like kernels with NURBS support: #gCAD3D, #Ayam, #Antimony, #libfive, #Seamless3d.