Bittersweet v3 from Flux:: is a free plug-in for managing audio transients. Turning the big wheel control to the sweet side softens the transient. Turning towards the bitter side, the transients are amplified. 

BitterSweet v3 also features a control for determining how the signal is to be processed. When the Main, the process affects the stereo signal. If Center is selected, only the M signal of the internal MS matrix is processed. If stereo is selected, only the S signal from the MS matrix is processed.
 
Three transient detection modes can be selected with varying periods of integration for transient. A Link function is provided to compensate the output gain with respect to the transient processing setting.
 
Bittersweet v3 is built around their latest 64-bit version 3 framework which has been designed to improve the processing performance dramatically. The graphic rendering in Bittersweet v3 uses a GPU-efficient 2D/3D graphic engine. This graphics engine was first introduced by Flux:: in their Pure Analyser System, is based on the OpenGL standard optimising the audio-to-visual experience utilising the GPU on the computer’s built-in graphics card.
 
Like all Flux:: plug-ins, Bittersweet v3 features 64-bit floating point processing, up to 8 channels. Note that Center and Stereo Modes are only available in stereo processing (2 channels).

Use the button above to go to the Flux website. Create a free account and download Flux Centre, their download manager software. use this to select and install Bittersweet.

BitterSweet v3 supports AU, VST, VST3, and both AAX Native and AAX DSP & AAX AudioSuite supports 32 bit for Pro Tools 10.3.5 and 64 bit in Pro Tools 11 and above.