Amethyst

Amethyst is a free, open-source tiling window manager for macOS inspired by xmonad on Linux. It automatically arranges your application windows into non-overlapping layouts so you never manually drag or resize anything. You open apps, Amethyst tiles them. The concept is simple: your screen is divided into regions, and each window fills a region. Open a terminal and a browser — they split the screen in half. Open a third app — the screen divides into thirds (or into a main pane plus a stack, depending on your layout). Close a window and the remaining ones instantly expand to fill the gap. This happens automatically, driven by whichever layout algorithm you've selected. Amethyst ships with about a dozen built-in layouts. Tall puts one main window on the left and stacks the rest on the right. Wide does the same but horizontally — main window on top, stack below. BSP (Binary Space Partitioning) recursively splits the screen so every window gets a proportional rectangle, which works well when you have 4-6 windows open. Fullscreen maximizes the focused window. Column arranges everything in equal vertical strips. You cycle through layouts with a keyboard shortcut and the windows instantly rearrange. Everything is keyboard-driven. Option+Shift+J and K move focus between windows. Option+Shift+Enter swaps the focused window into the main position. Option+Shift+H and L resize the main pane. Option+Shift+Space cycles layouts. These defaults use Option+Shift as the modifier, but you can remap them. The point is that you manage windows without touching your mouse, which is why tiling window managers are popular with developers who already live in the keyboard. Amethyst works with macOS Spaces and multiple monitors. Each Space can have a different layout. Each monitor tiles independently. You move windows between monitors and Spaces with keyboard shortcuts. The one macOS setting you absolutely must change: disable 'Automatically rearrange Spaces based on most recent use' in System Settings, or your Spaces will shuffle unpredictably. Why Amethyst over alternatives? It doesn't require disabling System Integrity Protection (SIP). Yabai, the other major tiling WM for macOS, needs SIP disabled for its full feature set, which many people aren't comfortable with. Amethyst works within macOS's accessibility APIs, so it's a safer choice for work machines and managed devices. The tradeoff is less customization — Yabai can do things Amethyst can't, like remove title bars or control window opacity. But for straightforward tiling with keyboard control, Amethyst is the practical choice. The honest assessment: if you've never used a tiling window manager, Amethyst will feel strange for the first few days. You're giving up the freedom to put windows wherever you want, and gaining the speed of never having to think about window placement again. Most people who try tiling for a week don't go back.