ATKCompressor + ATKExpander

The ATKCompressor and ATKExpander are based on Audio Toolkit and are 32- and 64-bit compatible on Windows and 64-bit compatible on Mac OS X 10.8 and above. You can also download the source code for free.
The ATKCompressor features attack, release, threshold, slope, softness and makeup gain controls.

The ATKExpander, that also serves as a noise gate, offers the same controls, only the makeup gain has been removed from the GUI.



http://matt.eifelle.com/2014/07/15/announcement-atkcompressor-1-0-1-atkexpander-1-0-1/