How can I install a single app from an unknown developer? I am new to Mac and am trying to install a Hex Editor.  Google sent me to "Hex Fiend", but, when I try opening it, I get "'Hex Fiend.app' can't be opened because it is from an unidentified developer."

How can I tell Mac to install and trust Hex Fiend? Ideally, I'd like to keep the setting of "identified developers only" and just make an exception this time.  Or, is there another Hex Editor I can use? I'd just like to be able to edit hex!



UPDATE: I tried the answers below, but they don't work, because I'm trying to do Open With from Finder (that is, click on the file, choose open with Hex Fiend).  Is there a way to do that? If not, how can I shut off this setting?
Very simply…

Right click it &amp; select Open.

That will bypass Gatekeeper for that one app

See: OS X: About Gatekeeper