Paste a column of SMILES or drop an SDF file, and every molecule comes back with a minimised 3D model, its 2D drawing beside it, and one SDF holding the lot.
The whole list is computed in your browser, so a file that would be too sensitive to upload anywhere is no different here from one that would not.
Conformers in 3D from a structure you draw. This tool needs JavaScript; these are the pages it offers: