QMForge is a GUI written by Dr. Adam Tenderholt during his PhD. He still maintains the code today, and keeps adding new features into the software.
It can be used to open and visualize output files of a list of modern computational packages, such as Gaussian 98/03/09/16, ADF, GAMESS (US), GAMESS (UK), PC-GAMESS, Jaguar, NWChem, ORCA, and QChem.
The key features including
Different population analysis (Mulliken, C-squared, Löwdin, etc)
Mayer bond orders
Fragment analysis
Track structures and energies through geometry optimization
Track the scan through potential energy surface
Visualize vibrational modes
Visualize simulated spectral results
Old versions of QMForge (V 2.4) can be downloaded free of charge using the link below