A window arrangement manager for macOS like BetterSnapTool and Magnet.
You can split the frontmost window to the left half of the screen, the left two-thirds, etc.

README for Japanese

You can also register your favorite keyboard-shortcuts for the command.

ShiftWindow works on macOS 14.0 or later.

1. Download Installer.dmg from releases page.
2. Double-click on the Installer.dmg.
3. Copy the App to the Applications folder.