Download of ShadowKiller 1.3 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The application lies within System Tools, more precisely System Optimization. The actual developer of this free software for Mac is Unsanity LLC.
From the developer:
ShadowKiller removes window and menu shadows in MacOS X. This changes the look of MacOS X completely, and speeds up its operation for slower Macs (such as G3). This was our first haxie, and it is distributed on a freeware basis. However, due to the nature of the haxie, we are unable to guarantee its operation for all configurations.
You may want to check out more software for Mac, such as WinShortcutter, Mac Pilot or AppTrap, which might be similar to ShadowKiller.