_{Built with AI — code, tests, design spec, and this README were written by Claude (Anthropic's Claude Code).}

tab-switch — a free, open-source macOS window switcher (AltTab alternative)

tab-switch is a free, open-source macOS window switcher. It replaces the native Cmd+Tab app switcher with two keyboard-driven switchers that cycle between windows, not just applications — a lightweight AltTab alternative for switching between windows on macOS.

• Cmd+Tab → switch between windows of all apps (replaces the native app switcher).
• Option+Tab → switch between windows of the current app only.

Both show a borderless text-list overlay (app icon + window title per row). Cycle with Tab / Shift+Tab while the modifier is held; the highlighted window is focused on release. Ordering is most-recently-used (MRU), so a single Cmd+Tab returns you to the previous window.

Why this exists

The native macOS Cmd+Tab switches between applications, not windows. If you have three browser windows, two terminals, and four editor windows open, the app switcher treats each app as a single entry — you land on an app and then have to fumble for the right window.

This tool flips the model: it switches between windows directly, regardless of which app owns them. The result is closer to the window-switching behavior on other platforms, with MRU ordering so the most common move (jump to the last window, jump back) is a single keystroke.

It is deliberately minimal — a personal tool, not a product. No settings UI and no code signing; it builds from source and installs via Homebrew.

How it compares

• vs. the native macOS switcher — Cmd+Tab on macOS switches between apps; tab-switch switches between individual windows, so you land on the exact window you want instead of an app.
• vs. AltTab — AltTab is a full-featured, open-source window switcher with window previews and rich configuration. tab-switch is a much smaller, keyboard-only alternative: a fast MRU text list, no thumbnails, no settings — if you want the leanest possible window switcher, this is it.
• Open source and free — MIT-licensed, builds from source, installs via Homebrew.

Requirements

• macOS 13 (Ventura) or later
• Xcode or the Swift command-line tools (Homebrew builds the app from source)
• Accessibility permission — required for both the keyboard event tap and window control.

Install

brew tap Zappendusta/tab-switch
brew trust zappendusta/tab-switch
brew install tab-switch
brew services start tab-switch

brew trust is required because Homebrew 6.0+ refuses to load formulae from third-party taps until you trust them. brew services start launches the agent now and auto-starts it at login. Then grant Accessibility permission in System Settings → Privacy & Security → Accessibility.

tab-switch is built from source, so each brew upgrade produces a new binary identity. macOS's permission system (TCC) treats that as a new app, so you must re-grant Accessibility after every upgrade.

The app runs as a background agent (LSUIElement): no Dock icon, no menu bar item. On launch it checks for Accessibility trust; if missing, it prompts and polls until granted, then starts automatically.

Usage

Keys	Action
Cmd+Tab	Open all-apps window switcher / step to next window
Option+Tab	Open current-app window switcher / step to next window
Shift+Tab (modifier held)	Step backward
Release modifier	Focus the highlighted window
Esc (modifier held)	Cancel without switching

A quick Cmd+Tab + release just flips to the previous window with no UI flash — the overlay only renders after a short hold or on the second Tab.

Development

swift build                              # build
swift test                               # run all tests (TabSwitchCore only)
swift test --filter MRUListTests         # run one test class
./scripts/make-app.sh [debug|release]    # build + bundle into tab-switch.app

swift run TabSwitchApp works, but the event tap requires the binary to be granted Accessibility, so the normal loop is ./scripts/make-app.sh && open tab-switch.app.

Architecture

Two SwiftPM targets, split by testability:

• TabSwitchCore — pure value/logic types, no AppKit or Accessibility imports, so it is unit-testable. The only target with tests.
• TabSwitchApp — the executable; all AppKit / Accessibility (AX) / CoreGraphics integration lives here.

The authoritative design is in docs/superpowers/specs/2026-06-27-tab-switch-design.md. For a detailed map of the core types and app wiring, see CLAUDE.md.

Keywords

macOS window switcher · switch between windows on Mac (not just apps) · free open-source AltTab alternative · Cmd+Tab window switcher · Option+Tab same-app window switcher · MRU window switching · keyboard window manager for macOS · lightweight alt-tab for Mac.

License

MIT — see LICENSE.