TeXShop (v 3.45.2) Release 11/11/2014
(Mountain Lion or Higher Strongly Recommended)
(for Lion, Mountain Lion, Mavericks, Yosemite)
TeXShop (v 2.47) Release 06/06/2012
(System 10.5 or Higher Strongly Recommended)
(for Systems 10.4, 10.5, 10.6)
Richard Koch
with contributions by Max Horn, Dirk Olmes, Mitsuhiro Shishikura, Seiji Zenitani,
Yusuke Terada, Martin Kerz, Isao Sonobe, and Many Others
TeX Live 2014 Release June, 2014
(For Intel and PPC, Leopard through Yosemite)
TeX Users Group (TUG) and MacTeX TeXnical working group

TeXShop is distributed under the GPL public license, and thus free.
TeXShop (v 3.45.2) requires Mac OS X 10.7 or later
TeXShop (v 2.47) requires Mac OS X 10.4.3 or later