I just installed the clipper today and quickly found out it wasn't working anywhere outside of Evernote's own site. Literally doing nothing when clicking the button. (Latest version of everything: OS X, Safari, the clipper.) I got it fixed by removing a Safari plugin. Removing plugins is easy - see this link; http://support.apple.com/kb/ts3230. All you have to do is delete the file, and restart Safari. Make sure to read this support article first though. It contains a list of plugins that should NOT be removed, and that cannot be reinstalled without reinstalling OS X. BE CAREFUL. I would also recommend removing plugins one by one, and checking if the clipper is working after each removal. In my case, the first one I removed was apparently the culprit, as the clipper is now working great. Well not on github, but that's unrelated to the Safari issue. jbignert: the interfering plugin was the citrix receiver; CitrixICAClientPlugIn.plugin. Maybe this'll help EN track down the issue?