brightctrl

Lightweight DDC/CI external monitor brightness controller — TUI + CLI. Native Rust binary, no ddcutil dependency.

Linux + Windows (x64). Linux drives DDC/CI over /dev/i2c-*; Windows uses the Monitor Configuration API. macOS isn't supported. On Windows, monitor names come from EDID and may fall back to a generic name if no driver is installed.

Run

npx brightctrl          # interactive TUI
npx brightctrl list     # list monitors
npx brightctrl get 1    # read brightness
npx brightctrl set 1 50 # set monitor 1 to 50%

Or install globally:

npm i -g brightctrl
brightctrl              # also: bctrl, bc

On install, a prebuilt binary is downloaded from the matching GitHub release (Linux/x64 or Windows/x64). Needs network access.

TUI keys

| Key | Action | |-----|--------| | ↑ ↓ | select monitor | | ← → | adjust brightness | | g / 0 | 100% / 0% | | S | sync mode (all monitors together) | | P | precise mode | | r | refresh / re-detect | | / | type an exact value | | ? | help | | q | quit |

Mouse: drag / click / scroll the bar; click the Sync / Precise toggles.

Permissions

Windows needs no extra setup (enable DDC/CI in the monitor OSD if list is empty). On Linux, reading and writing brightness needs access to /dev/i2c-*. Add yourself to the i2c group (or run as root):

sudo usermod -aG i2c $USER   # then re-login

If /dev/i2c-* is missing, load the module: sudo modprobe i2c-dev.

Other install methods

• Arch / AUR: yay -S brightctrl
• Binary: download from Releases, chmod +x, drop in $PATH.

License

MIT