Quilt

Quilt automatically arranges Mac windows as they open, then reflows the remaining windows when one closes. Choose Grid, Columns, Rows or Side layouts, with support for up to five windows per screen. Extra windows stack in a tile with a chip for switching between them.

Designed for people who work across multiple windows, Quilt also supports keyboard shortcuts, drag-to-resize behavior, focus mode, per-screen settings, custom spacing and borders, always-floating apps, and a Fill mode. It runs from the menu bar and can pause while Stage Manager is active.