Downloading jVisualizer 2.5 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This free Mac app is a product of jSoftware.
From the developer:
Coupling patterns in NMR spectroscopy are sometimes not easy to understand. With jVisualizer you've got a intuitive tool to reconstruct the patterns found in your experiment. In a second step you can type in the chemical shifts and calculate the coupling constants. jVisualizer is also a good tool for teachers to demonstrate how complex coupling patterns are formed.