Open Extract .7z Extension On Mac OSX

The official 7zip doesn't support Mac to open .7z extension. The are number of tutorials out there that are outdated and don't support Mountain Lion. Anyways, here is a tutorial on how open and extract the 7z archive for free using a utility :

1) UnArchiver a light weight extractor, get it on the Mac App store from here. (It's free.)

2) That's it. You can now open .7z extension on your Mac. 

Unarchiver will also open extensions like Zip, RAR, 7-zip, Tar, Gzip and Bzip2. Many older formats, such as StuffIt, DiskDoubler, LZH, ARJ and ARC if need be.