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 13.0 or later.

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