CADability is a pure .net class library for modeling and analyzing 3d data, both with your code and interactively. It comes with an optional Windows.Forms user interface, which can be adopted to other environments. It does not refer to other 3d modeling libraries. For data exchange you can use STEP, STL or DXF files.
TryGetCodePagethat supports code page values without underscore for https://github.com/SOFAgh/CADability/issues/171