Opta

Window switcher · macOS 14+

Hold ⌥. Pick a window. Let go.

Opta cycles every window on your Mac from one key you are already resting a thumb on. The overlay draws in 0.274 ms — roughly three percent of a ProMotion frame — so the list is simply there.

Download for macOS Build from source View source

Universal build for Apple Silicon and Intel · macOS 14 or newer · all releases

Hold ⌥ Option — or press and hold here

Speed

Faster than the frame it lands in

Speed is the whole point, so it is the thing this project measures and defends. A switcher only feels instant if it finishes before the display asks for the next frame. Opta finishes with the frame barely started — and every number below is instrumented in the shipping build, not estimated.

0.274ms
Median warm overlay render, measured over repeated sessions with OSSignposter intervals on the shipping build.
0 ms8.33 ms — one 120 Hz frame
0.274 ms median render 2.236 ms 95th percentile The remaining 6.09 ms of the frame is still yours.
3.3%of a 120 Hz frame spent drawing the overlay
2.236ms95th percentile render, against a 4 ms ceiling
0.04%of one core while idle, measured over 45 s resident
0.5MBcompiled binary, arm64
0depsthird-party packages in the whole build
66tests in 16 suites, run on every change

How these were taken. Render figures come from OverlayRender signpost intervals on warm sessions — the second and later invocations, which is what a switcher actually does all day. The budget is the ceiling the project holds itself to: below 1 ms median and 4 ms p95, or the visual change gets simplified until it fits. Footprint and test figures are read from the shipping build. Repeat-session preview and icon lookups are served from cache and cost effectively nothing.

Shortcuts

Four keys, and nothing to learn

Every shortcut is Option plus one thing. Hold to browse, release to commit — the same muscle memory you already have for Command-Tab, moved to the key beside it.

⌥+⇥

Cycle every visible window, from every application, most recently used first.

⌥+`

Cycle only the windows of the app you are already in. Switch it off from the menu bar if you type à, è, ì, ò, or ù.

⇧+ either

Walk the list backwards. Overshoot by one and you are one keystroke from home.

escorclick

Escape dismisses without activating anything. Hovering selects, clicking activates immediately.

Ordering

It starts on the window you want

Opta keeps its own most-recently-used order. It records focus as it happens — windows it activates itself, application switches from the Dock or Command-Tab, and focus changes inside each app — and falls back to the system's front-to-back list for windows it has never seen focused.

The first press lands on the second window, not the first. The window you are staring at is skipped, because you are already there. One tap of Option-Tab flips you back to where you just were; hold it to go further.

Minimised and hidden windows stay out of the list. So do Opta's own.

  • Xcode — OptionMark.swiftyou are here
  • Safari — Quiet Glass specfirst press
  • Terminal — ~/code/opta
  • Finder — Applications
  • Mail — Inbox

Internals

Native the whole way down

No Electron, no helper daemon, no bundled runtime. Opta is 2,807 lines of Swift across 27 files, calling the frameworks that already ship with your Mac.

CGWindowListCopyWindowInfo

Discovers every visible window, then filters the untitled ghosts that other switchers show you.

ScreenCaptureKit

Captures live window previews, cached between sessions so a repeat press costs nothing.

Accessibility APIs

Raises exactly the window you chose, and nothing else that happens to belong to the same app.

CGEventTap

A session event tap intercepts Option-Tab and Option-backtick without swallowing anything else.

SMAppService.mainApp

Registers Opta as a login item through the modern API, no legacy helper bundle.

SwiftUI + NSPanel

One borderless transparent panel, one material, one shadow. The Quiet Glass surface you see above.

Permissions

Three prompts, and why

A window switcher cannot work without reaching outside its own process. Here is exactly what Opta asks for and what it does with each. Nothing leaves your Mac.

Accessibility

Required. Focuses and raises the window you selected. Without it Opta can show you the list but cannot act on it.

Input Monitoring

Required. Lets the event tap see Option-Tab globally, so the switcher works from inside any app.

Screen Recording

Optional. Draws the live previews. Decline it and Opta falls back to application icons; everything else still works.

Install

Download it, or build it

Every tagged version is built, tested, and published on GitHub as a universal binary. Building it yourself takes two commands and skips one macOS annoyance.

Download

Take the latest release

Grab Opta.zip from the releases page, unzip it, and move Opta.app into Applications. It runs on Apple Silicon and Intel.

Latest release

These builds are signed but not notarised by Apple, so macOS quarantines the download and says it cannot verify the developer. One command clears it: 

xattr -dr com.apple.quarantine /Applications/Opta.app

Each release carries a different signature, so macOS asks for permissions again after an update. Browse all releases for checksums and notes.

Build

Compile from source

The build script assembles the bundle and signs it with a stable local identity, so there is no quarantine prompt and permissions survive every rebuild.

# clone and build
git clone https://github.com/romankhadka/opta.git
cd opta && ./scripts/build_app.sh

# run it
open .build/release/Opta.app

Needs Xcode 26 or its command line tools.

Either way: macOS 14 or newer. Grant the permissions when prompted, then relaunch so macOS applies them.