STEP (ISO 10303)

STEP is the ISO standard for exchanging exact 3D solid models. It describes geometry as precise mathematical surfaces (B-rep and NURBS), not triangles, so a cylinder is stored as a true cylinder.

Used by: Mechanical design tools such as SolidWorks, Fusion 360, Inventor, CATIA, Creo, Onshape and FreeCAD — it is the default “send me the model” format between them.