Fractal Explorer's source code can be found on its Git repository at https://github.com/Yalir/FractalExplorer. See below to download ready-to-use binaries.

Fractal Explorer 1.0 binaries (September 9th, 2012)

Operating System File
Mac OS X 10.5 and Mac OS X 10.6 Fractal Explorer for Mac OS X 10.5 and Mac OS X 10.6.zip (1.6MB)
Mac OS X 10.7 and later Fractal Explorer for OS X.zip (5.4MB)
Windows XP and later Fractal Explorer.zip (1.2MB)

Note for WindowsYou first need to download the Visual C++ 2010 Redistributable Package and install it, except if the installer tells you that you already have a more recent version installed.