Windows-style window switcher for macOS.
One Option-Tab: every open window, most-recent first, on the screen where your mouse is.
macOS Cmd-Tab switches between applications. AltTab switches between windows — just like Alt-Tab on Windows. Hold Option, tap Tab to see every open window as a thumbnail, cycle through them, and release to switch.
Download the latest AltTab.dmg →
Open the .dmg, drag AltTab to Applications, and launch it. Grant Accessibility when prompted (System Settings → Privacy & Security → Accessibility).
This build is not yet notarized. On first launch macOS blocks it: open System Settings → Privacy & Security, click Open Anyway, and launch again (or clear the quarantine flag with
xattr -dr com.apple.quarantine /Applications/AltTab.app).
Homebrew:
brew install --cask sergio-farfan/tap/alttabThe fully qualified name trusts just this cask (Homebrew 6+ requires third-party taps to be trusted before their code runs). To use the short name instead, run brew trust sergio-farfan/tap && brew tap sergio-farfan/tap first, then brew install --cask alttab. Update later with brew upgrade --cask alttab — until releases are notarized, each upgrade of this ad-hoc-signed build needs the Open Anyway step once more (Homebrew only carries a Gatekeeper approval forward when the signing identity is stable).
Prefer to build it yourself? See Build from source.
lwouis/alttab is the feature-rich, highly configurable incumbent. This project is the deliberately minimal alternative:
- Tiny and auditable — ~2,700 lines of pure Swift + AppKit, single purpose.
- Zero dependencies — no packages, no frameworks bundled.
- No Screen Recording permission — titles via the Accessibility API, app icons instead of live thumbnails (avoids the recurring macOS 15 recording prompt). Live window previews are available as a strictly opt-in toggle on macOS 14+.
- Windows-style Option-Tab semantics with menu-bar-only footprint (no Dock icon).
If you want extensive customization, use lwouis/alttab. If you want something small you can read end to end, use this.
- Option-Tab to activate, cycle with Tab, confirm on release
- Shift-Tab / Arrow keys to navigate in reverse — and Option-Shift-Tab opens the switcher already cycling backward, anchored on the least-recently-used window (new in 1.3.2)
- Escape to cancel without switching
- Instant response — the window list is kept warm by a debounced background refresh between invocations, window-raise runs off the main thread, and app icons are cached, so the switcher appears immediately with fresh contents even after hours of idle (1.3.2)
- Window titles via Accessibility API — works for all apps without Screen Recording permission
- App icon display with graceful fallback (no Screen Recording prompt on macOS 15+)
- Includes minimized windows, ⌘H-hidden apps, and windows on other Spaces
- Optional live window previews (ScreenCaptureKit, macOS 14+, opt-in from the menu)
- Appearance override (System / Light / Dark) and background styles: Solid (default), Transparent, or native Liquid Glass (macOS 26+) with a Glass Strength setting — Light / Medium / High / Max
- Multi-monitor aware — the switcher opens on the screen with the mouse pointer
- MRU (most recently used) ordering with intra-app focus tracking — resilient to busy apps: a wedged app's Accessibility timeout can't drop its windows from the list or scramble their order (1.3.2)
- Menu bar utility — no Dock icon, no clutter
- Launch at Login support (macOS 13+ SMAppService)
- Zero dependencies — pure Swift + AppKit
- ~2,700 lines of code, single-purpose, auditable (83 unit tests on the pure-logic core)
git clone https://github.com/sergio-farfan/alttab-macos.git
cd alttab-macos
./build.sh install
open ~/Applications/AltTab.appThen grant Accessibility permission when prompted (System Settings → Privacy & Security → Accessibility).
| Requirement | Details |
|---|---|
| macOS | 13.0+ (Ventura or newer) to run |
| Xcode | 26 or newer to build from source (the code references NSGlassEffectView, which only exists in the macOS 26 SDK); full install from App Store, not just Command Line Tools |
First time with Xcode?
If you just installed Xcode, you may need to run:
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
sudo xcodebuild -license accept
sudo xcodebuild -runFirstLaunchInstalls to ~/Applications — no sudo required.
./build.sh installInstalls to /Applications — requires sudo.
sudo ./build.sh install --system| Command | Description |
|---|---|
./build.sh build |
Build only (Release configuration) |
./build.sh install |
Build and install to ~/Applications |
./build.sh install --system |
Build and install to /Applications (sudo) |
./build.sh run |
Build and launch from build directory |
./build.sh clean |
Remove build artifacts |
./build.sh uninstall |
Remove from ~/Applications |
./build.sh uninstall --system |
Remove from /Applications (sudo) |
On first launch, AltTab will prompt for Accessibility access. Screen Recording is optional.
| Permission | Required | Why |
|---|---|---|
| Accessibility | Yes | CGEvent tap for global hotkey detection; AXUIElement for window titles, window management, focus tracking, and unminimize |
| Screen Recording | No (opt-in) | Only for the optional "Show Window Previews" feature (macOS 14+, ScreenCaptureKit) |
Grant in: System Settings → Privacy & Security → Accessibility
Note: Screen Recording permission is not required. Window titles are read via the Accessibility API, and app icons are used instead of live thumbnails. This avoids the repeated "Screen & System Audio Recording" prompt on macOS 15 (Sequoia). Enabling Show Window Previews in the status menu is the only thing that requests Screen Recording; with the toggle off (the default) the API is never touched.
macOS pins each Accessibility grant to the code identity of one specific build. Ad-hoc-signed releases get a new identity every build, so after updating AltTab the toggle in System Settings still shows ON while the new binary is silently denied. Fix:
tccutil reset Accessibility com.alttab.app
open ~/Applications/AltTab.app # or /Applications — grant again when prompted(Equivalently: remove AltTab from the Accessibility list with the − button and re-add it.) This re-prompt-per-update goes away once releases are signed with a stable Developer ID certificate.
| Shortcut | Action |
|---|---|
| Option + Tab | Open switcher, select next window |
| Option + Shift + Tab | Open switcher cycling backward (least-recent window first) |
| Tab | Cycle forward (while holding Option) |
| Shift + Tab | Cycle backward |
| ← → | Navigate left / right |
| Release Option | Switch to selected window |
| Escape | Cancel, dismiss switcher |
| Enter | Confirm selection |
| Click thumbnail | Select and switch |
AltTab installs a CGEvent tap at the session level to intercept keyboard events globally. A 3-state machine (idle → active → idle) tracks Option hold/release and Tab presses. The event tap includes retry logic with exponential backoff to handle the case where the Accessibility subsystem isn't ready at login time. Window enumeration combines CGWindowListCopyWindowInfo (on-screen windows) with AXUIElement queries (minimized windows). Window titles are read via AXUIElement (kAXTitleAttribute), which only requires Accessibility permission — no Screen Recording needed. MRU order is maintained via NSWorkspace activation notifications and per-app AXObserver callbacks that track focused-window changes — including intra-app switches like Cmd-`. Between invocations, those same events schedule a debounced, rate-limited background re-gather, so the cached window list the switcher opens from is never stale — even on the first Option-Tab after hours of idle.
The switcher UI is a non-activating NSPanel (.nonactivatingPanel style mask) so it floats above all windows without stealing focus. App icons are displayed for each window, served from an in-memory cache (prewarmed at launch) so the panel paints immediately instead of resolving each icon through LaunchServices on the fly. Window activation uses AXUIElement to raise the specific window and unminimize if needed; that synchronous AX IPC runs on a background queue with a bounded messaging timeout, so a slow target app can't block the main thread (and stall the switcher).
AltTab/AltTab/
├── main.swift # App entry point — wires NSApp delegate manually
├── AppDelegate.swift # Lifecycle, menu bar status item, orchestration, session epochs
├── HotkeyManager.swift # CGEvent tap plumbing; decodes events for the state machine
├── SwitcherStateMachine.swift # Pure Option-Tab session state machine (unit-tested)
├── SwitcherSelection.swift # Pure per-session selection: initial anchor, cycling, reconcile (unit-tested)
├── WindowModel.swift # CGWindowList + concurrent AX pass per app, warm cache + async refresh
├── MRUOrder.swift # Pure MRU ordering (unit-tested)
├── GatherMerge.swift # Pure carry-over policy for lossy AX gathers (unit-tested)
├── Debouncer.swift # Trailing-edge debouncer for the background cache refresh (unit-tested)
├── WindowCapture.swift # Opt-in ScreenCaptureKit window previews (macOS 14+)
├── SwitcherPanel.swift # NSPanel overlay with selectable background (solid / HUD / Liquid Glass)
├── ThumbnailView.swift # Individual window cell (preview/icon + title + app name)
├── WindowActivator.swift # AXUIElement window raise / unminimize (off-main, bounded timeout)
├── PermissionManager.swift # Accessibility polling; Screen Recording preflight/request
└── PreferencesMenu.swift # Status bar menu (Launch at Login, Appearance, Background, Window Previews, Quit)
./build.sh uninstall # Remove from ~/Applications
sudo ./build.sh uninstall --system # Remove from /ApplicationsOr manually delete AltTab.app and remove from Login Items in System Settings.
- Fork the repo
- Create a feature branch (
git checkout -b feature/my-feature) - Make your changes
- Test:
./build.sh run - Commit and push
- Open a Pull Request
MIT — Sergio Farfan (sergio.farfan@gmail.com)