Low Wave Studios SpikeQ

Best for surgical multiband transient shaping. SpikeQ is a free multiband transient shaper available in 64-bit AU and VST3 formats for macOS and Windows. Multiband transient shapers are quite rare, especially when they are free. That’s why this gem from Low Wave Studios should probably find a place in your plugin arsenal. SpikeQ combines standard transient shaping controls—attack, sustain/release, and gain—with 4 semi-parametric EQ bands (low/high shelves and 2 peak bands).

This added EQ functionality lets you boost specific frequencies within the transient portion of the sound for more surgical precision. The plugin features an aggressive transient shaping algorithm with an x2 Amount switch for more extreme effects, but it can also apply subtle boosts without becoming harsh. It also includes a clipper section with oversampling to reduce aliasing and phase distortion while remaining CPU-efficient.

The GUI is fine, but there’s a bit of a learning curve involved until you figure out how the whole thing operates.