If you just do a start/end point it will create a cubic with 2 endpoints and 2 control points. But if you drop a whole series of points (up to 12 I think) it will create a curve that passes though all of them. This is done by internally creating a bunch of cubic splines where the control points are automatically positioned and not shown. You still get 2 control points for the derivatives at the ends, unless you create a closed loop.
https://solvespace.com/
If you just do a start/end point it will create a cubic with 2 endpoints and 2 control points. But if you drop a whole series of points (up to 12 I think) it will create a curve that passes though all of them. This is done by internally creating a bunch of cubic splines where the control points are automatically positioned and not shown. You still get 2 control points for the derivatives at the ends, unless you create a closed loop.