One little known feature in Safari is that within the application package there is a file that lists all of the plug-ins you have installed.
There are a couple ways to access it.
The most straightforward way to access the file is to select “Installed Plug-ins” from the “Help” menu in the Safari menu bar.
Another way is to copy the following file path into any web browser:
file:///Applications/Safari.app/Contents/Resources/English.lproj/Plug-ins.html
The third way and least practical way to do view the list of plug-ins is to select the Safari application, Control-Click on the file, select “Show Package Contents,” and then open the file, which is titled “Plug-ins.html” in ~/Contents/Resources/English.proj.