Molden is a visualisation software for QM calculations.
The home page is
The current version is 5.8
The program can be downloaded by anonymous ftp from
cd pub/molgraph/molden
A precompiled version for Ubuntu Linux is avaliable in
cd pub/molgraph/molden/bin/Linux
It worked well 2021.

You can build molecules by the Z-mat editor (primitive, but working)
Click on add Line
Select the element
Click on the atom to which it should bind, another to form an angle and a third to form a dihedral.