GifBuilder...?

I'm looking for a version of GifBuilder that is compatiable with OSX.
I've downloaded two versions one from twocows and one from versiontracker.com- Neither will open.
After downloading I doubleclick the icon on the desktop to install and it
pops up shortly as an active program on my dock, then disappears.
What is going on!? Can someone tell me how to open this or a different
program to download?

TIA