Otto
Per-app volume for Windows, done right. One hand on the mouse, no key held, nothing to install.
Unsigned: on a new PC Windows SmartScreen may show "Windows protected your PC" once. Choose More info → Run anyway.
What it does
▤The mixer
Click the normal Windows speaker icon (or press Ctrl+Alt+V) and get every app that has audio: icon, slider, live meter, mute. Drag it anywhere and it stays open.
↕Scroll on the taskbar
Wheel over an app's taskbar button changes that app's volume, no key needed. Hover shows its level. Over the clock or empty taskbar: master volume.
⌥Alt + scroll anywhere
Hold Alt and scroll over any window, full-screen games included, to change that app's volume. The modifier is configurable.
◔Start level for new apps
The moment an app opens its audio, before you hear anything, Otto sets it to your start level (50 % by default). Per-app rules give some apps their own, or leave them alone.
◎One pill, one place
Every change shows a small glass pill at a fixed spot: top, center or bottom of the screen the mouse is on. Your choice.
▣Quiet by design
Lives in the tray, opens no window on start, one small exe. Settings in %APPDATA%\Otto, or next to the exe in portable mode.
↻Updates itself
Otto checks GitHub twice a day. When a new version is out, the tray menu shows Update to vX: one click downloads it, verifies its checksum, swaps the exe and restarts. Settings stay.
Looks like this
Cheat sheet
| Do this | Result |
|---|---|
| Click the speaker tray icon | Opens Otto's mixer instead of the Windows slider. Right-click stays Windows'. |
| Ctrl+Alt+V | Opens the mixer where the mouse is. Configurable. |
| Wheel over a taskbar button | That app's volume. Hovering shows the level pill. |
| Wheel over clock / tray / empty taskbar | Master volume. |
| Alt + wheel over a window | That app's volume, wherever the window is, games included. |
| Click an app's icon in the mixer | Mute / unmute it. |
| Drag the mixer, or click its pin | It stays open until Esc, the pin, or the tray. |
| Right-click Otto's tray icon | Open mixer · Settings · Start with Windows · Quit. |
Settings
Quick adjust
Taskbar scrolling, hover pill, speaker-icon click, the Alt gesture and its modifier (Alt, Ctrl+Alt, Shift+Alt, Ctrl+Shift), the wheel step (1 / 2 / 5 %), pill on/off and its position.
Mixer
The hotkey, start with Windows.
Updates
Check for updates, install the new version in one click, or turn the automatic check off.
New apps
The default start level and per-app rules: an app can have its own start level or be left alone. Apps already playing when Otto starts are never touched.
Install & run
Grab the portable zip from the latest release, unzip anywhere (a folder on your tools drive is perfect).
It appears in the tray. Click the Windows speaker icon to see the mixer.
Settings → "Start Otto when Windows starts". For a USB stick, drop an empty file named portable next to the exe and it keeps its settings there.
Command line: Otto.exe --quit asks a running Otto to exit, Otto.exe --autostart starts it and switches start-with-Windows on, Otto.exe --update-now updates a fresh start to the latest release, Otto.exe --probe out.json is a headless self-test.
Good to know
Admin apps
Apps running as administrator do not receive the scroll gestures unless Otto itself runs elevated (Windows rule). The mixer still controls them.
Loudness ≠ volume
A video mastered louder than the voice chat next to it is a loudness problem, not a volume one. Windows' per-app meter cannot tell the two apart, so Otto does not pretend to; Windows' own "Loudness Equalization" (device properties → Enhancements) flattens everything system-wide if you want that.
Build it yourself
.NET 8 SDK, then dotnet publish (see the README in the repo). C#, WPF, NAudio for Windows Core Audio.
Changelog
- Fixed the move from Fader: right after updating, 0.4.0 could stop halfway through starting. An updated
Fader.exenow hands over to a freshOtto.exeand removes itself.
- Fader is now Otto, after Otto Suwen from Re:Zero, the merchant who hears every voice around him. New green look from his cloak.
- Updating from Fader keeps your settings and start-with-Windows, and replaces
Fader.exewithOtto.exeby itself.
- Built-in updater: Check for updates in the tray menu and in Settings, automatic check twice a day, one-click install with checksum verification.
- Install 0.3.0 by hand once; every later version arrives through the app.
- The level pill sits at one fixed spot (top / center / bottom, your pick) instead of jumping around.
- Removed the per-app volume cap (apps never raise their own session volume, so it had nothing to do).
- Scroll over taskbar buttons without a key, hover pill, speaker-icon click opens Otto.
- Drag or pin the mixer to keep it open; resizable, scrollable Settings.
- Portable self-contained build;
--quitand--autostart. - Removed the loudness guard and the blur option.
- First version: mixer flyout, Alt+scroll, start level and cap rules, tray icon, hotkey.