BrightSync

Website: https://bberka.github.io/BrightSync/

BrightSync is a tray app for Windows and Linux that keeps the brightness of your monitors aligned to one shared master brightness value.

Platform	Architectures	Packages
Windows 10/11	x64, x86, arm64	Setup installer, portable zip
Linux (glibc)	x64, arm64, arm	.deb, .rpm, Arch .pkg.tar.zst, AppImage, portable .tar.gz
Linux (musl, Alpine)	x64, arm64, arm	.apk, portable .tar.gz
Linux (any other architecture)	riscv64, loongarch64, x86, ...	portable framework-dependent .tar.gz (needs a .NET 10 runtime)

Linux setup details, desktop environment notes, and troubleshooting are in LINUX.md. Maintainers: ARCHITECTURE.md and PACKAGING.md.

BrightSync provides its own master brightness control (available in the tray popup or settings menu) to manage all supported displays from one place, including your laptop's built-in integrated screen and external DDC/CI monitors.

It also includes optional automatic brightness, idle dimming, per-monitor limits, and recovery features for monitors that forget their brightness after sleep or power changes.

Design Philosophy

BrightSync is built around the philosophy of "Configure once, and never think about monitor brightness again."

• Set and Forget: Brightness rules, limits (min/max), multipliers, and curves are configured per-monitor once. The app handles the rest dynamically.
• No Micromanagement: Avoid unnecessary per-monitor brightness controls in the daily quick menus.
• Extensible Integration: Leverage a robust CLI engine rather than building bloated internal systems (e.g., custom hotkey managers).

Screenshots

Quick menu

Settings window

What BrightSync Does

• Uses one global master brightness value as the source for all enabled monitors.
• Supports independent master brightness control that does not rely on Windows' native slider.
• Treats the internal display (laptops) as a standard controllable target (WMI on Windows, the backlight class on Linux).
• Applies brightness to external monitors through DDC/CI.
• Lets you adjust each monitor (both internal and external) with its own enable flag, minimum, maximum, and multiplier (ratio).
• Supports advanced monitor hardware controls (Contrast, Volume, RGB Gains, Color Presets, and Input Source) for compatible DDC/CI external monitors.
• Can drive brightness automatically from a 24-hour curve instead of manual input.

Features

• Works on both laptops and desktops
• Tray icon with hover tooltip (displays current master brightness, mode, and active states) and quick brightness popup
• Independent master brightness slider in the tray or settings
• Automatic brightness based on a smooth 24-hour curve
• Visual curve editor in Settings
• Windows Energy Saver detection with configurable brightness reduction
• Quick "Eye Protection" mode (dimming) with configurable duration and reduction amount (applied to all targets including internal)
• Quick "Brightness Boost" mode (brightening) with configurable duration and increase amount (applied to all targets including internal)
• Per-monitor enable or disable control (both internal and external)
• Per-monitor minimum brightness, maximum brightness, and multiplier (ratios)
• Per-monitor hardware controls for external displays, allowing you to configure Contrast, Volume, RGB Color Gains (Red, Green, Blue), Color Presets, and active Input Source directly from the UI
• Optional idle dimming after inactivity
• Optional pause while the session is locked
• Optional brightness enforcement to re-apply values if a monitor changes them
• Layered monitor detection: WMI and DisplayConfig fallbacks on Windows, DRM/EDID on Linux
• Layered brightness backends: internal panel (WMI or backlight), low-level DDC/CI (dxva2 on Windows, /dev/i2c-N on Linux), Windows high-level monitor APIs, and write-only capability fallbacks
• Apple display and Apple Studio Display detection with backend diagnostics
• HDR-aware monitor metadata and safer enforcement behavior
• Per-monitor detection diagnostics in Settings
• Redacted, bounded diagnostics export from Settings > About for troubleshooting
• Optional legacy DDC/CI detection mode for compatibility
• Refresh monitors from the tray or Settings window
• Configurable periodic monitor refresh to automatically recover lost DDC/CI connections
• CLI command routing for brightness and resident app actions
• Dynamic system theme syncing on Windows (style changes apply automatically without restarting)
• Compiled with Native AOT for single-file, zero-dependency execution with low memory footprint and instant startup
• Start with Windows / start at login (XDG autostart on Linux)
• GitHub release update checks (installed automatically on Windows; Linux updates come from your package manager or a new download)

Requirements

• Windows 10 (19041) or newer, or a Linux desktop with X11 or XWayland
• One or more DDC/CI-compatible external monitors for external brightness control

Important notes:

• BrightSync controls external monitors through DDC/CI or high-level monitor APIs.
• Built-in laptop panels are controlled via WMI (Windows) or /sys/class/backlight (Linux) and treated as a normal monitor target.
• A monitor may still appear in the app even if BrightSync cannot change its brightness.

Feature support by platform

Feature	Windows	Linux
External monitors (DDC/CI) incl. contrast, volume, RGB gain, presets, input	Yes	Yes (needs /dev/i2c-N access, see LINUX.md)
Laptop panel brightness	Yes (WMI)	Yes (backlight class, logind fallback)
Tray icon, quick popup, settings window	Yes	Yes (StatusNotifierItem tray)
Automatic curve, eye protection, boost, enforcement	Yes	Yes
Idle dimming, ignore while media plays	Yes	Yes on X11 sessions and on GNOME Wayland (Mutter, KDE or X11 idle; MPRIS media); hidden on other Wayland compositors
Pause while locked	Yes	Yes (logind, GNOME and KDE screensavers)
Energy Saver / Power Saver reduction	Yes	Yes (power-profiles-daemon)
Start at login	Yes (registry)	Yes (XDG autostart)
Refresh rate switching, ICC color profile, HDR info	Yes	Not available
Automatic update install	Yes	No, update notice only

Install

Windows

1. Open the latest release.
2. Download the installer for your CPU (BrightSync-Setup-v<version>-win-x64.exe, -win-arm64.exe, or -win-x86.exe), or the matching portable .zip.
3. Run the installer, or extract the zip anywhere and run BrightSync.exe.

Linux

Download the package for your distribution and CPU from the latest release:

Or install (and update later) the latest Linux release with the hosted script:

curl -fsSL https://raw.githubusercontent.com/bberka/BrightSync/master/install.sh | bash

Run the same command again to update. For a system-wide install, pass --system and run it with root privileges:

curl -fsSL https://raw.githubusercontent.com/bberka/BrightSync/master/install.sh | sudo bash -s -- --system

Uninstall a per-user installation with --uninstall. Your settings are kept:

curl -fsSL https://raw.githubusercontent.com/bberka/BrightSync/master/install.sh | bash -s -- --uninstall

For a system-wide installation, run:

curl -fsSL https://raw.githubusercontent.com/bberka/BrightSync/master/install.sh | sudo bash -s -- --system --uninstall

sudo apt install ./BrightSync-<version>-linux-x64.deb        # Debian, Ubuntu, Mint
sudo dnf install ./BrightSync-<version>-linux-x64.rpm        # Fedora, RHEL, openSUSE (zypper)
sudo pacman -U ./BrightSync-<version>-linux-x64.pkg.tar.zst  # Arch, Manjaro
sudo apk add --allow-untrusted ./BrightSync-<version>-linux-musl-x64.apk  # Alpine
chmod +x BrightSync-<version>-linux-x64.AppImage && ./BrightSync-<version>-linux-x64.AppImage
tar xzf BrightSync-<version>-linux-x64.tar.gz && ./BrightSync-*/install.sh  # any distro, per-user

Replace x64 with arm64 or arm for ARM devices. See LINUX.md for monitor access setup and tray notes.

Daily Use

1. Start BrightSync.
2. Adjust brightness with the BrightSync tray icon and quick popup slider (or via the settings window).
3. Open Settings for monitor-specific options and advanced behavior.

Behavior to know:

• When automatic brightness is off, the slider works normally.
• When automatic brightness is on, BrightSync controls the brightness value and the slider becomes read-only.
• The quick popup includes Automatic Brightness, Eye Protection, and Brightness Boost toggles for fast control.
• Right-click the Eye Protection or Brightness Boost menus in the tray for time duration presets.
• Most settings changes are only persisted after clicking Save.

Command Line

BrightSync also supports command-line commands through BrightSync.exe on Windows and brightsync on Linux. Examples below use BrightSync.exe.

On Windows, the Flow Launcher plugin lets you control brightness and BrightSync modes with the bs keyword. It requires Flow Launcher 2.x, Python 3, and BrightSync running in the tray.

Resident-aware behavior:

• If BrightSync is already running in the tray, CLI commands are forwarded to the running app through a localhost-only command server.
• If BrightSync is not already running, only direct brightness commands run one-shot and then exit.
• Resident-only commands never auto-start the tray app.
• Manual CLI brightness commands respect automatic brightness. If automatic brightness is enabled, manual CLI brightness changes fail until auto mode is turned off.

One-shot-capable commands:

BrightSync.exe brightness set 55
BrightSync.exe brightness up 10
BrightSync.exe brightness down 10

Resident-only commands:

BrightSync.exe status
BrightSync.exe status --json
BrightSync.exe settings show
BrightSync.exe monitors refresh
BrightSync.exe auto on
BrightSync.exe auto off
BrightSync.exe eye-protection on
BrightSync.exe eye-protection on --hours 3
BrightSync.exe eye-protection off
BrightSync.exe boost on
BrightSync.exe boost on --hours 2
BrightSync.exe boost off
BrightSync.exe app exit

status is read-only and reports the resident app's current master brightness, automatic-brightness state, timed eye-protection/boost state and expiry, monitor counts, and a UTC timestamp/version. It requires BrightSync to already be running; it never starts a resident app or touches monitor hardware when no resident instance is available. Use status --json for the stable, source-generated machine-readable form.

Startup behavior:

• BrightSync.exe starts the normal tray app.
• BrightSync.exe --autostart starts the resident tray app hidden, the same way Windows startup and the Linux autostart entry use it.

Settings Overview

Brightness

• Adjust the shared brightness value when automatic brightness is off.

Monitor Configs

• Enable or disable individual monitors.
• Clamp each monitor with minimum and maximum brightness.
• Scale a monitor brighter or dimmer with a multiplier.
• Expand any monitor row to see detection diagnostics, fallback details, and advanced hardware controls (if supported by DDC/CI).

Advanced Hardware Controls

If an external monitor supports DDC/CI capability command probing, expanding its row in Settings exposes additional hardware adjustments:

• Contrast: Adjust the display's hardware contrast value.
• Volume: Change the monitor's built-in speaker volume (if equipped).
• RGB Gains (Color Warmth): Adjust individual Red, Green, and Blue subpixel gains to fine-tune color balance.
• Color Presets: Select from supported factory color temperatures and presets (such as sRGB, Display Native, 5000K, 6500K, 9300K, or User Defined).
• Input Source: Digitally switch the active monitor video input (e.g. HDMI 1, HDMI 2, DisplayPort 1, DisplayPort 2, USB-C, VGA, DVI).

Note on performance & persistence: Sliders for Contrast, Volume, and RGB Gains utilize a 150ms debounce window to prevent stuttering and display lag during interactive dragging, while Color Preset and Input Source dropdowns apply instantly. All values are saved to the configuration file (config.json) and re-applied when the application starts or when monitors are refreshed.

Automatic Brightness

• Enable a 24-hour brightness curve.
• Drag curve points in Settings to tune brightness through the day.
• Lock automatic brightness is a legacy toggle that is ignored as BrightSync handles display brightness independently from the native Windows slider.

Other Options

• Start with Windows
• Legacy DDC/CI detection
• Disable on lock screen
• Idle dimming
• Eye protection mode
• Brightness boost mode
• Energy saver reduction
• Brightness enforcement
• Check for updates

Compatibility and Troubleshooting

• BrightSync uses a layered detection pipeline. It combines DDC/CI enumeration with DisplayConfig and WMI-based metadata fallbacks to improve monitor naming and connection detection.
• BrightSync also uses layered external brightness control detection. If a low-level DDC/CI brightness read fails, it can fall back to the Windows high-level monitor API or a write-only capabilities path when supported by the display.
• Apple displays, including Apple Studio Display when Windows exposes a usable brightness backend, are identified in diagnostics.
• Use Settings > About > Advanced Diagnostics > Export to save a bounded JSON report. It includes allowlisted app, runtime, configuration-mode, monitor backend, support, connection, and capability summaries; it does not upload data or include raw logs, native handles, tokens, or configuration file contents.
• HDR-capable displays are detected through DisplayConfig. When HDR is active, BrightSync avoids aggressive brightness readback enforcement on that display.
• Open a monitor row in Settings to see which detection backend was used and what fallback path BrightSync took.
• If monitor detection is unreliable, enable Legacy DDC/CI detection, then refresh monitors or restart the app.
• Legacy DDC/CI detection uses a compatibility-focused enumeration path and may help on systems where richer metadata detection is unreliable.
• Advanced Hardware Controls & Presets: Some monitors lock or disable physical RGB gain adjustment controls on the hardware side when a specific Color Preset (e.g., sRGB) or picture mode is selected. If you find the Red, Green, or Blue sliders disabled or unresponsive, try changing the Color Preset dropdown to User Defined or Display Native. Additionally, internal laptop panels do not support DDC/CI VCP features and will not show the Advanced Hardware Controls section.
• If Disable on lock screen is enabled, BrightSync pauses external monitor reads and writes while the session is locked and refreshes monitors after unlock.
• Idle dimming can either scale targets down by a percentage or reduce each monitor (including the internal display) to its configured minimum brightness.
• Energy saver reduction automatically dims all monitors when the OS power saver is on (Windows Energy Saver, Linux power-saver profile).
• Eye protection mode provides temporary manual dimming by subtracting a fixed number of brightness points from all monitors.
• Brightness boost mode provides a temporary brightness increase by adding a fixed number of brightness points to all monitors.
• Eye protection mode and Brightness boost mode are mutually exclusive. Enabling one turns the other off.
• Brightness enforcement helps recover from monitors that reset brightness after sleep, power cycling, or input changes.
• Automatic brightness recalculates through the day and after resume or system time changes.

Configuration

BrightSync stores its files at:

	Windows	Linux
Config	%APPDATA%\BrightSync\config.json	~/.config/BrightSync/config.json
Logs	%APPDATA%\BrightSync\Logs	~/.config/BrightSync/Logs
Command server metadata (while running)	%LOCALAPPDATA%\BrightSync\command-server.json	~/.local/share/BrightSync/command-server.json

The config format is identical on both platforms.

Updates

BrightSync checks GitHub releases for updates. On Windows it can download, verify (SHA-256), and install the matching installer. On Linux it shows an update notice and opens the releases page; rerun the hosted installer command in the Linux section to update.

Build Locally

Requirements: .NET 10 SDK. Native AOT publishing also needs the platform C++ toolchain (Visual Studio C++ tools on Windows, clang and zlib1g-dev on Linux).

dotnet restore
dotnet build BrightSync.sln
dotnet test --project tests/BrightSync.Tests.csproj --filter-not-trait "Category=Hardware" --filter-not-trait "Category=Integration"

The target OS follows the host, or the -r runtime identifier when given. To compile the other platform's graph without running it:

dotnet build src/BrightSync.App/BrightSync.App.csproj -r linux-x64      # from Windows
dotnet build src/BrightSync.App/BrightSync.App.csproj -r win-x64 -p:EnableWindowsTargeting=true   # from Linux

Publish (Native AOT): dotnet publish src/BrightSync.App/BrightSync.App.csproj -c Release -r <rid>. Linux packages: packaging/build-linux.sh <rid> <version> <out> (see PACKAGING.md).

Release Automation

This repository uses GitHub Actions to build and publish releases.

• Workflow: .github/workflows/release.yml
• Automatic trigger: change VERSION (the minor number only, see Versioning) and push to main or master
• Manual trigger: run the workflow from the GitHub Actions tab
• Output packages: Windows x64, x86, arm64 (setup installer and portable zip), Linux x64, arm64, arm for glibc and musl (deb, rpm, pacman, AppImage, apk, tar.gz), and the portable framework-dependent Linux archive. Asset names and the checksum manifest are described in PACKAGING.md.

The workflow builds version 0.<VERSION>.<next patch>, publishes every target, smoke-tests the Linux x64 and arm64 packages under a virtual display, and uploads the assets plus BrightSync-SHA256SUMS.txt to the matching GitHub release.

Versioning

BrightSync follows 0ver: the major version is always 0 and there will never be a 1.0. The VERSION file holds only the minor number (19 means 0.19.x). Bump it for a new minor release; the patch number is chosen by the release workflow as the next unused v0.<minor>.<patch> tag. Pull request builds are versioned 0.<minor>.0-pr<number>.<run>.