I am interested in predicting the NMR spectrum of small organic compounds. It doesn't matter to me if the prediction is very accurate. I'll eventually be comparing the prediction to experimental results.
It looks as if several free online tools offer the ability to do such predictions:
NMR DB is a free website that offers a prediction of 1H, 13C, and supposedly even 2D NMR experiments. Structures are entered via a GUI editor.
VeSPA and PyGamma are Python packages (or Python wrappers around C libraries) that supposedly simulate NMR spectra of molecules. However, both packages are very old and have not been substantially updated in some time.
My question is, what is the best available (free) computational tool for predicting NMR spectra? As I mentioned, I understand that predictions are imperfect. What software, if any, are widely used by practicing chemists for NMR simulation? What is the best reference to read about such software, including the heuristics and algorithms it uses to simulate spectra? Is Vespa and/or PyGamma state of the art? The NMR DB site is nice, but I'd very much prefer an interface that is amenable to scripting, and where structures could be supplied computationally rather than via a GUI interface.
(I'm a mass spectrometrist and biochemical engineer with little training in NMR methods.)