ZL Audio has released ZL Splitter, a free multi-mode signal splitting utility for macOS, Windows, and Linux.
This is the latest entry in ZL-Audio’s (and no, it’s not short for Zlatic Audio, although I wish it were!) growing lineup of open-source mixing tools, alongside the ZL Compressor and ZL Equalizer.
ZL Splitter is designed to give you more control over your audio signal by splitting it into two complementary parts, which can be processed independently.
You can split the incoming audio in several ways, such as Left/Right, Mid/Side, Low/High, Transient/Steady, and Peak/Steady. Then, you can basically apply your effects chain to each signal path separately before recombining them.

The flexibility you get for building complex FX setups is pretty neat. For example, in Low/High mode, you can send the lows to one effects chain (maybe saturation or multiband compression) and the highs to another (such as stereo widening or modulation).
Transient/Steady mode is where things get even more interesting. It uses an FFT-based algorithm to isolate transients from steady-state content.
I’ve found this especially useful for taming harsh percussion or adding effects only to sustained elements while preserving the transient. Pretty cool stuff for cinematic sound design!
Each split type comes with dedicated controls. In Transient/Steady mode, for instance, you can adjust Strength, Balance, Hold, and Smooth, letting you fine-tune the separation to your needs. Peak/Steady mode works more like a dynamics processor with controls that resemble a compressor.
The plugin also features real-time metering, giving you a clear representation of what’s happening under the hood.
Another neat feature is that the UI allows you to flip the outputs with the press of a button, which can be handy for quickly testing your routing.
ZL Splitter also supports automation for all parameters, and settings like the filter structure and slope can be adjusted to fit your workflow. FIR filters preserve phase, while SVF filters introduce phase shifts, so knowing when to use each is crucial for transparent mixing.
All things considered, this one’s a nice pick if you’re into using creative routing, parallel processing, or mid/side tricks for your FX chains.
ZL Splitter is available in VST3, AU, and LV2 formats for macOS, Windows, and Linux, and it’s completely open-source under the AGPLv3 license.
You don’t need to register or install any license manager. Just head to the GitHub page, download the appropriate version for your OS, and start experimenting.
Download: ZL Splitter
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Last Updated on September 4, 2025 by Tomislav Zlatic.