Snap Cat

left / right / fill / minimize for macos — one file, zero bloat

windows that click into place · starring Snapu

Snap Cat is the smallest useful window manager for macOS. Four shortcuts. A menu bar icon. Accessibility APIs. No drag-to-snap, no preference pane, no updater, no account.

The mascot is Snapu — the little window cat who snaps panes into place.

If you want Rectangle with every tile preset — use Rectangle. If you want modifier + arrows and nothing else — use this.

git clone https://github.com/stevederico/snapcat.git
cd snapcat
./build.sh
open -a SnapCat

1. Grant Accessibility when prompted (or System Settings → Privacy & Security → Accessibility → enable Snap Cat)
2. Quit and reopen Snap Cat once so the grant sticks
3. Press ⌘← on any window (or pick another modifier under Modifier Key)

Default modifier is ⌘. Change it in the menu bar → Modifier Key (⌘ / ⌥ / ⌃). Persists.

Not macOS Full Screen. Fill uses the screen's visible frame so the window stays a normal windowed app.

• Left / right halves on the display under the window
• Fill to all usable space (not Stage Manager / Full Screen theater)
• Minimize via Accessibility, same as the yellow button

• Typing wins — in a real text field (non-browser apps), mod← / mod→ stay line nav
• Browsers always snap — Brave, Chrome, Safari, Arc, etc. never pass through (sites park focus in sidebars like x.com Grok)
• Terminals snap — Warp, Terminal, iTerm, and friends always get window actions (their UI is one big text view)

• Status item with Snap Left / Right / Fill / Minimize
• Keyboard Shortcuts checkmark — disable global hotkeys without quitting (persists)
• Modifier Key — Command / Option / Control (persists)
• Accessibility Settings… deep link when the grant goes missing
• Menu actions still work when hotkeys are off

• One Swift file — the whole app lives in Sources/main.swift
• No preference window — settings live in the menu bar
• No network — no updater, analytics, or phoning home
• Menu bar only — LSUIElement, no Dock icon

./build.sh compiles a release binary, wraps it in SnapCat.app, codesigns, and copies to /Applications.

./build.sh
# → /Applications/SnapCat.app

Signing (Accessibility grants stick better with a stable code signature):

# Default in this repo: your Apple Development identity (if present)
./build.sh

# Ad-hoc sign (works everywhere; may need re-grant after rebuilds)
SNAPCAT_SIGN_ID="-" ./build.sh

# Custom identity
SNAPCAT_SIGN_ID="Apple Development: Your Name (TEAMID)" ./build.sh

Install somewhere else:

SNAPCAT_INSTALL="$HOME/Applications" ./build.sh

If the Accessibility dialog keeps popping up: System Settings → Privacy & Security → Accessibility → remove every Snap Cat entry → enable the one from Applications → restart Snap Cat.

Menu bar icon → Quit Snap Cat, or:

pkill -x SnapCat

1. A CGEvent tap watches key-downs for pure chosen modifier + arrow (no extra modifiers).
2. If focus is a real text field, the key is left alone (line / document navigation).
3. Otherwise Snap Cat swallows the event and resizes or minimizes the front window via Accessibility.
4. Frames use NSScreen.visibleFrame so menu bar and Dock remain visible.

Heavy Accessibility tree walks are intentionally not done on the hotkey path — they can timeout the event tap and leak keys (e.g. browser back/forward).

git clone https://github.com/stevederico/snapcat.git
cd snapcat
./build.sh
open -a SnapCat

Keep it small. New tile layouts, prefs panes, and updaters are usually out of scope — open an issue first if you're unsure.

• 🐦 X: @stevederico
• 🐛 Issues: GitHub Issues

• Rectangle — the gold standard; Snap Cat is the opposite end of the spectrum
• Apple Accessibility and Quartz Event Services — the whole app is a thin shell over these

./build.sh && open -a SnapCat

Grant Accessibility. Press mod←. Done.

MIT License — use it however you want. See LICENSE for details.