Why open source matters
Window managers interact with every other app on your Mac via the Accessibility API. That's a level of system access where you want to be able to verify what the software actually does. Open source tools let any developer read, audit, and compile the code themselves — a meaningful trust advantage over closed-source utilities.
All three of the top Mac window managers are open source. You're not giving up quality by refusing to pay: the free alternatives are better-maintained and more actively developed than most of their paid rivals.
The essential apps
Rectangle App
The go-to recommendation for anyone who wants keyboard-driven window snapping without configuration overhead. Halves, thirds, quarters, corners, multi-display shortcuts — all free, all open source, works out of the box.
Amethyst
Open source xmonad-inspired tiling manager. Windows automatically arrange into layouts you cycle through with a shortcut. Steeper learning curve, but a powerful free tool for users who want true tiling.
Yabai
An open source scriptable tiling window manager with a full shell API. Pairs with skhd for hotkeys. The most powerful free option — also the most complex to configure.
Where to start
Rectangle first, always
Whether you end up staying with Rectangle App forever or eventually move to Amethyst or Yabai, start here. It's the fastest path from "my windows are a mess" to "every window is exactly where I want it" — and it costs nothing.
Open source, actively maintained, trusted by hundreds of thousands of Mac users, and updated for every new macOS version. Rectangle is the essential open source Mac window utility.
Get Rectangle freeFrequently asked questions
Is Rectangle truly open source?
Yes — Rectangle is released under the MIT licence. The full source is publicly available; you can read, fork, or compile it yourself.
Are there open source alternatives to Moom?
For everyday snapping: Rectangle. For automatic tiling: Amethyst. For scripted layout automation: Yabai. Together these three open source tools match or exceed everything Moom does, at zero cost.
How often is Rectangle updated?
Rectangle App is actively maintained and typically releases macOS compatibility updates within days or weeks of Apple shipping a new system version — often faster than paid alternatives.