ATKColoredExpander

ATKColoredExpander, a free and Open Source compressor plug-in, for 64-bit Mac OS X (10.9 minimum) and Windows (32 and 64-bit) in VST2, VST3 and AU plug-in formats.
The plugin now use the JUCE framework and is optimized for SSE4.2 processors on MacOS and AVX processors on Windows.
This plugin requires universal runtime libraries on Windows as per Microsoft recommendation (see the blog post for more details).

http://blog.audio-tk.com/2017/11/28/announcement-atkcoloredexpander-2-0-0/

Dead Duck Free Effects Bundle

The Effects Bundle provides 24 original VST audio effect plugins covering everything from essential mixing tools such as EQ, compression and limiting to creative sound shaping tools such as delays, modulation effects and reverb:

• AutoFilter.
• AutoPan.
• BitCrusher.
• Channel.
• Chorus.
• Compressor.
• DeEsser.
• Delay.
• DualFilter.
• Equaliser.
• Expander.
• Filter.
• Flanger.
• Gate.
• Limiter.
• MonoDelay.
• Overdrive.
• Phaser.
• Reverb.
• RingMod.
• SigGen.
• TiltEQ.
• Tremolo.
• Utility.

http://deadducksoftware.blogspot.com.es

AudioToolkit ATK

• AutoSwell
• Limiter
• Expander
• Compressor
• Chorus
• Delay
• Phaser
• ...

https://sourceforge.net/projects/audiotoolkitplugins/files/

ATK Colored Compressor & Expander

ATKColoredCompressor - a compressor with a color section modulating gain around the threshold.
ATKColoredExpander - an expander with a similar color section.

http://matt.eifelle.com/2015/09/15/announcement-atkcoloredcompressor-1-0-0-and-atkcoloredexpander-1-0-0/

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/