BetterSnapTool runs in the background as a menu bar app. It lets you manage your window positions and sizes by either dragging them to one of the screen’s corners or to the top, left or right. You can also set keyboard shortcuts in order to move and resize your windows.
Simply drag the window to one of the sides of the screen and it snaps there. Every open Mac window can be resized into the top, bottom, left or right half of your screen size. You can also use keyboard shortcuts or the menu bar to manage your Mac windows.