Yta

A window manager that lives in the Mac menu bar. Drag a window towards the top of the screen, a zone palette grows out of the edge, and dropping the window over a zone snaps it there.

Drag to a zone: Halves, thirds, two-thirds and one-third, and a 2×2 grid. The palette appears during the drag and goes away when you let go.; The zone under the pointer is marked while you move, so you can see where the window will land before you release it. Release outside every zone and nothing moves.
Keyboard shortcuts: Control-Option-Left and Control-Option-Right place the focused window in the left or right half. Control-Option-Up fills the visible area of the screen, without entering full screen.; The same three layouts are in the menu bar menu, with their shortcuts next to them.
Out of the way: Yta has no Dock icon and no window of its own. It is the menu bar symbol and the palette during a drag, and nothing else.; It can open when you log in. Windows are placed on the screen they are already on, inside the visible area, so the menu bar and the Dock keep their space.
Why it needs permission: macOS has no public interface for moving another app's window. Yta uses the system's accessibility interface instead, and asks for permission under System Settings → Privacy & Security → Accessibility the first time it runs.; It reads and writes the position and size of the focused window in the moment. It stores nothing about your windows and has no network connection.
The top edge is shared: macOS has its own gestures at the same edge: tiling by dragging to the screen edges, and Mission Control opening when a window is dragged to the top. They take over before the zone palette can be reached.; Turn both off under System Settings → Desktop & Dock to give the palette that edge. The keyboard shortcuts work either way.
Requirements: A Mac running macOS 14 or later.