Kliohearts’ software line is a treasure trove of effects. But Kliohearts Essentials alone is an impressive free collection of standalone plug-ins for anyone. You won’t want to sleep on the latest addition, Compactor, a deceptively simple “precision ducking” tool.
Here’s how it works: if your budget is exactly zero and you don’t own any other Kilohearts stuff, you’ll still want to grab Essentials as an impressive collection of free effects. Kilohearts is betting, wisely, that those will get you hooked on their approach to effects design, which emphasizes precise tools and no-frills UIs that cut straight to the point. (Did anybody else grow up with Exacto knives with all the clever tips? Like that.)
Kilohearts’ claim to fame is their hosts — Phase Plant, Multipass, and Snap Heap — which let you combine these utility modules into instruments and effects, in a semi-modular style. If you do own those, you’ll still want to grab the freebies, as doing so adds these tools to your collection for use in those hosts. But if not, you can still use the routing setup of your host of choice. (It’s handy having the standalone tools sometimes, too.)
That’s some 34 modules in the free collection now:

Compactor is an especially notable addition. On the surface of it, it’s a ducking tool — attack, hold, release, threshold, and amount. You can optionally sidechain signal, but otherwise, Compactor will just use the active input signal and duck as that input crosses the threshold. We’ve got nice extras, though: stereo correlation options, plus RMS, PEAK, and “ISP” modes — that last one follows all peaks in he waveform, even at the sub-sample level.
Here’s their intro/guide:
And full walkthrough:
Blog post:
Introducing Kilohearts Compactor
Download:
https://kilohearts.com/products/compactor
VST/AAX/AU for Mac and Windows, plus Khz’ own “Snapin” format.
Oh, I would love to see these come to Linux, where they’d complement tools like Sinevibes really well. (Maybe someone has gotten them working via wrappers?)
Time for some effects processing now; see you.