AudioMixer

Per-app volume control for macOS, inspired by the Windows Volume Mixer.
Lives in the menu bar. Turn any app down — or boost it up to +24 dB.

macOS has one volume slider for everything. When a video call is too quiet next to your music, or a browser tab is blasting while you work, your only option is to turn everything up or down.

AudioMixer gives every app its own fader, like the Volume Mixer on Windows. Lower Slack notifications, push a quiet call above 100 %, mute a game while keeping your music — straight from the menu bar.

Contents

• Install
• Features
• Uninstall
• Troubleshooting
• How it works
• Build from source
• Related projects

Install

Paste this in Terminal:

curl -fsSL https://raw.githubusercontent.com/Zahorrr/AudioMixer/main/install.sh | bash

It downloads the latest release, installs it in /Applications and launches it. Look for the sliders icon in your menu bar.

Prefer a regular installer? Download AudioMixer.pkg from the latest release. It isn't signed with a paid Apple Developer ID, so macOS will warn you the first time — see Troubleshooting.

Requirements: macOS 14.2 or later, Apple Silicon or Intel.

Features

A volume for every app

Each app that uses audio gets its own vertical fader with a live level meter, and a mute button underneath. The Device column on the left controls your speakers or headphones as a whole. Double-click a value to snap back to 100.

Boost beyond 100 %

Above the 100 mark, the fader turns orange and amplifies the app — up to +6, +12, +18 or +24 dB, your choice. A soft limiter rounds off the peaks so boosted audio stays clean instead of crackling.

A clean list

Apps are shown the way you know them. Chrome's, Claude's or Safari's background audio processes are grouped under the app itself, and system processes stay out of the way. Right-click any column to reset it or hide the app; bring it back later from Settings.

Set it and forget it

Your levels are remembered per app and applied again as soon as the app plays sound — even after a restart. AudioMixer launches at login by default. Apps you leave at 100 are never touched, so they get zero added latency.

Settings

Open them from the ⚙️ in the mixer, a right click on the menu bar icon, or ⌘ ,:

• Language — English or Français
• Launch at login
• Maximum boost
• Hidden apps, with a Show button for each

Uninstall

1. Right-click the menu bar icon and choose Quit.
2. Move AudioMixer from /Applications to the Trash.

To remove everything, including your saved levels:

osascript -e 'quit app "AudioMixer"'
sudo rm -rf /Applications/AudioMixer.app
defaults delete io.github.zahorrr.AudioMixer
sudo pkgutil --forget io.github.zahorrr.AudioMixer

You can also remove it from System Settings › Privacy & Security › Screen & System Audio Recording and System Settings › General › Login Items.

Troubleshooting

An app goes silent when I move its fader

AudioMixer needs permission to capture audio from other apps. Open System Settings › Privacy & Security › Screen & System Audio Recording and turn AudioMixer on. After an update, macOS may ask again.

"Apple could not verify AudioMixer…"

macOS shows this for any downloaded app that isn't notarized by Apple. Open System Settings › Privacy & Security, scroll down and click Open Anyway — or remove the quarantine flag before opening the installer:

xattr -d com.apple.quarantine ~/Downloads/AudioMixer.pkg

The curl install doesn't trigger this warning.

The menu bar icon disappears after I click it

That's your menu bar manager (Ice, Bartender, Hidden Bar…) hiding it again. Move AudioMixer to its always visible section, or hold ⌘ and drag the icon to the right of the manager's divider.

An app isn't in the list

Apps only appear while they have audio open. If it still doesn't show up, check Settings › Hidden apps.

Known limitations

• Audio is played on the default output device. An app that sends its sound to another device isn't controlled.
• Each app is mixed down to stereo, on the first two channels of the output.

How it works

No kernel extension, no virtual audio driver. AudioMixer uses the Core Audio process taps API introduced in macOS 14.2:

1. A CATapDescription with muteBehavior = .mutedWhenTapped captures an app's audio and silences it at the source.
2. A private aggregate device combines the current output device with that tap.
3. An IOProc applies the gain (smoothed per buffer, soft-clipped near 0 dBFS) and plays the result back.

When an app sits at 100 % and is playing, an unmuted tap only feeds the level meter — the audio itself is left alone.

Build from source

Requires the Xcode Command Line Tools (xcode-select --install).

git clone https://github.com/Zahorrr/AudioMixer.git
cd AudioMixer
scripts/build.sh install   # build for this Mac, install in /Applications, launch
scripts/build.sh pkg       # universal build + dist/AudioMixer.pkg

File	Role
Sources/AppTap.swift	Process tap + aggregate device + real-time render (gain, limiter, peak meter)
Sources/MixerModel.swift	App discovery & filtering, per-app state, tap lifecycle, persistence, language
Sources/MixerView.swift	SwiftUI mixer: vertical faders, meters, mute buttons
Sources/SettingsView.swift	Settings: language, launch at login, boost, hidden apps
Sources/CoreAudioHelpers.swift	Core Audio property helpers, process → app resolution
Sources/AudioMixerApp.swift	Menu bar item, popover, right-click menu, settings window
Resources/	Info.plist and app icon
scripts/	swiftc build, ad-hoc signing, install, .pkg packaging

Related projects

• BackgroundMusic — free and open source, the project that inspired this one. Per-app volume through a virtual audio driver, plus auto-pausing your music player.

License

MIT — see LICENSE.