Monitor Brightness Control

A small, fast desktop app for controlling brightness, contrast, color temperature and input source on every monitor connected to your machine — your laptop's built-in panel and every external DDC/CI display. Written in Rust, packaged with Tauri 2; the shipped binary is ~7 MB and has no Electron or Node runtime.

Features

• All your monitors, one window. Per-display sliders for brightness; for external monitors, also contrast and the standard color presets (sRGB, Native, 5000K – 9300K, User).
• System tray. Right-click for per-monitor brightness submenus, quick "Apply profile" picker (visible as soon as you have one), night-mode toggle, and a one-click way to bring the window back.
• Global hotkeys. Brightness ±, night mode, blackout, show/hide window — all configurable; defaults to Ctrl+Shift+Up/Down/N/B.
• Per-app profiles. Bind a profile to an executable (firefox.exe, cs2.exe, com.apple.Safari, the WM_CLASS on Linux) and it auto-applies whenever that app gets focus. Or leave the app id empty and trigger the profile manually from the tray menu.
• Schedules. Time-of-day rules — apply a brightness preset at 08:00 on weekdays, dim everything after 22:00, target individual monitors or all of them. Times use your system's local timezone.
• Auto-dim. Smoothly transitions between day and night brightness around your local sunrise/sunset for the configured latitude/longitude. Fully offline, sun-position math runs locally.
• Multi-monitor sync. Optionally keep secondary displays at a fixed offset from your primary.
• Six languages out of the box. English, German, Spanish, French, Italian, Japanese. The app reads your OS locale by default.
• Autostart toggle. First-class operating-system autostart (no scheduled-tasks-XML hackery).
• CLI (mbc). Drives the same Rust core, scriptable from your dotfiles, Home Assistant, AutoHotkey, etc.

Screenshots

Monitors — brightness, contrast and color-preset per display. Real EDID names (PHL 27E1N1800A, AUS XG27UCS); status badge for external vs internal.	Profiles — per-app overrides with sliders, no JSON. App identifier is optional — empty profiles apply manually from the tray. Each monitor's overrides toggle independently.
Settings (top) — startup, language, hotkeys, auto-dim coordinates.	Settings (bottom) — schedules, multi-monitor sync. The tab scrolls; these are the top and bottom views.
System tray — per-monitor brightness submenus, "Apply profile" picker (visible once you have a profile), night-mode toggle.	About — version, links, license, and the as-is disclaimer in your locale.

Platform support

Platform	Internal panel	External (DDC/CI)	Hot-plug	Status
Windows 10 / 11	WMI WmiMonitorBrightnessMethods	dxva2 Low-Level Monitor Configuration API with cached PHYSICAL_MONITOR handles	WM_DEVICECHANGE (cache invalidation)	✅ Primary development target — Windows 11 Pro 26200 with 3× DDC/CI displays
macOS 11+	DisplayServices.framework (private), CoreDisplay_Display_SetUserBrightness fallback	IOAVService over DCPAVServiceProxy (m1ddc-style path)	IOServiceMatching re-enumeration	⚠ Compiles; needs hardware to validate the IOAVService pairing
Linux	/sys/class/backlight/*/brightness	/dev/i2c-* with I2C_SLAVE ioctl	udev (drm, i2c-dev)	⚠ Compiles; install 90-monitor-brightness.rules for non-root use

Install

• Microsoft Store — coming soon.
• Direct download — pre-built installers on the Releases page.
• Linux distros — AppImage, .deb, Flatpak (manifest in packaging/linux/).
• macOS — .dmg, notarized in CI. Mac App Store submission is not recommended because the IOAVService path uses private symbols.

Build from source

git clone https://github.com/kingchenc/MonitorBrightnessControl
cd MonitorBrightnessControl

# CLI only — no Node toolchain needed
cargo build --release -p brightness-cli
./target/release/mbc list
./target/release/mbc set --id 'win:\\.\DISPLAY1#0' 60

# Full Tauri app (release exe in target/release/)
cd app && npm install && npm run build && cd ..
cargo build --release -p monitor-brightness-control --features custom-protocol

The --features custom-protocol flag is what makes a direct cargo build produce a working app — cargo tauri build would set it automatically. Detailed packaging, signing, MSIX and Flatpak instructions: docs/BUILDING.md.

CLI quick reference

mbc list                                  # show every monitor + current brightness
mbc set --id <id> 60                      # set one monitor to 60%
mbc set 80                                # set every monitor to 80%
mbc up 10                                 # step every monitor up by 10%
mbc vcp get --id <id> --code 0x12         # read raw VCP feature (contrast in this case)
mbc vcp set --id <id> --code 0x14 --val 5 # set color preset to 6500K

Architecture

brightness-core is the entire portable surface: a MonitorManager trait with platform-specific backends under crates/brightness-core/src/platform/. Both brightness-cli and the Tauri app are thin wrappers around it.

Notable design choices, all documented in docs/ARCHITECTURE.md:

• DDC/CI handles are cached and serialized with a mutex — the OS APIs are not thread-safe in the way you'd hope.
• Brightness/contrast reads are kept in a per-monitor cache so the UI and tray menu don't pay a 50–300 ms DDC/CI roundtrip on every render.
• Heavy enumeration runs on a background thread after the window appears — startup feels instant even on machines where WMI brightness queries are slow.
• The foreground-window watcher polls (~750 ms on Windows, 1 s on macOS/Linux) rather than hooking — much simpler and the latency is invisible at human time scales.

Privacy

The app makes no network calls. It does not phone home. It does not collect telemetry. It writes its config to your OS's standard config directory (%APPDATA%\MonitorBrightnessControl\ on Windows, ~/Library/Application Support/MonitorBrightnessControl/ on macOS, ~/.config/MonitorBrightnessControl/ on Linux). See docs/PRIVACY.md.

Contributing

Bug reports, platform fixes (especially the macOS IOAVService path) and additional languages are welcome via pull request. See CONTRIBUTING.md for the full guide, the inbound-license terms, and the development setup.

Disclaimer

This software is provided as-is, with no warranty of any kind. The author does not assume liability for any damage to monitors, hardware, OS settings, or data resulting from use of this software. DDC/CI writes go straight to display firmware; some monitors don't follow the spec cleanly and may behave unexpectedly. Use at your own risk.

License

Source-available, proprietary. Copyright © 2026 kingchenc. All rights reserved. See LICENSE.

Quick summary — read the LICENSE for the actual terms:

You may	You may not (without written permission)
Run the official binaries — personal use, internal business use, on any number of devices you own or control.	Modify, adapt or fork the code.
Read the source code in this repository.	Redistribute the Software or any modified copy in source or binary form.
Submit pull requests, bug reports and feature ideas.	Sell, rent, sublicense or repackage it as a paid product.
	Reverse-engineer the binaries (beyond what local law mandates).

This is not OSI-approved Open Source — it is "source-available". The dependencies (Tauri, the Rust ecosystem) remain under their own MIT / Apache-2.0 licenses; their notices are reproduced in THIRD-PARTY-NOTICES.md. Only the first-party code in this repository is covered by the proprietary terms above.