I built a per-app audio mixer for macOS as a solo dev

macOS doesn't have per-app volume control. It's had one volume slider since forever. Windows has had per-app audio since Vista. I finally got annoyed enough to build my own. What I built SoundPrism is a menu bar app that gives you individual volume, EQ, compression, and output routing for each app running on your Mac. It also allows you to record audio per app, either dry, wet or both at once! There are two ways to use it. A quick popover from the menu bar handles volume, mute, and basic EQ. Hit ⌘⇧C and you get a full mixing console with channel strips, VU meters, EQ curves, and compressor metering for every app. Some engineering details The whole thing is Swift, built on native Apple audio frameworks. No kernel extensions, no third-party audio drivers. Each app runs through a real-time DSP chain: 10-band biquad IIR equalizer 3-band multiband compressor (Linkwitz-Riley crossovers) Brick-wall peak limiter Stereo widener and crossfeed processor Everything on the audio thread is lock-free