Peek

A native macOS window switcher that replaces ⌘-Tab — and learns which apps you actually use.

Peek takes over the system ⌘-Tab switcher with a left-side column of live window previews, per-app CPU/RAM, one-keystroke quit and pin, a built-in dashboard of your switching habits, and an order that gets smarter the more you use it.

Overrides the macOS switcher — same keys

Peek intercepts ⌘-Tab at the system level (a CGEventTap), so you keep the exact muscle memory you already have — hold ⌘, tap Tab — but get Peek's column instead of Apple's. The native switcher never appears. Prefer a different trigger? Switch it to ⌥-Tab or ⌃-Tab in Settings.

Smart ordering — the whole point

Most switchers show windows in a fixed order. Peek ranks them by how you actually work, using two independent layers:

🧠 Sticky apps (opt-in learning, off by default)

A lightweight learning layer scores every app by recency-weighted switch frequency (a 7-day half-life), so the more you switch to an app, the higher Peek floats it — automatically. Your busiest apps drift to the top and are always the first keystroke away, while apps you've cooled on quietly sink. Each row shows an affinity meter (signal bars) so you can see what Peek has learned. A first-run window explains it with a live demo; enable it there or anytime from the menu-bar icon. Until you do, Peek behaves like a classic ⌘-Tab. The window you're leaving always stays at index 0, so a quick ⌘-Tab-release is still "flip to the last app."

📌 Pinning (always on)

Pin the apps you always want first with the 📌 button on any row (or from the dashboard). Pinned apps float to the top of the switcher independently of the learning layer — always there, whether or not sticky apps is on.

Together: pins give you a fixed home row; sticky apps orders everything else by real usage.

📊 Switching Insights

A built-in dashboard (SwiftUI + Swift Charts) turns your switching history into a picture of how your workflow actually works — total switches, active days, busiest hour, most-used app, switches per day, top apps, hourly rhythm, and your most common app-to-app transitions. The "Your apps" panel shows the exact order that drives the switcher, with inline pinning.

It's also the foundation for what's next: because Peek already understands your transitions and rhythms, it can grow customizable, per-user workflows — surfacing the right set of apps for the task you're in, at the time of day you usually do it. The data is already there; the automation is the roadmap.

Everything else

• Live previews, RAM-lite — only the selected window's thumbnail is ever captured, one at a time, via ScreenCaptureKit.
• Per-app CPU / RAM — each row shows the app's live CPU% and memory, sampled only for the visible windows, only while the switcher is open (a cheap per-pid proc_pid_rusage call — no global scan, no background polling).
• Live system footer — CPU, memory, and battery at the bottom of the column.
• Quit from the switcher — Q/W or the ✕ button quits the highlighted app; hold ⌥ to force quit. The row disappears immediately.
• Keyboard-first — while holding the modifier: Tab/⇧Tab cycle, ↑↓ navigate, 1–9 jump straight to a window, Home/End go to first/last, P pins.
• Settings — theme, light/dark, animations, switcher position (left/center), max rows, which display & Spaces, menu-bar icon shape & tint, hidden apps, and every shortcut toggle.
• 5 languages — English, Español, 中文, العربية (RTL), Français.
• Auto-update — ships with Sparkle; Check for Updates… is in the menu.

Install

bash setup-signing.sh   # once: stable self-signed identity (permission grants then persist)
bash make-app.sh        # builds + installs /Applications/Peek.app
open /Applications/Peek.app

Peek lives in the menu bar. First launch prompts for two permissions:

1. Accessibility — to intercept ⌘-Tab and raise windows.
2. Screen Recording — to read window titles and capture thumbnails.

Grant both in System Settings → Privacy & Security, then relaunch. (A stable signature keeps the grants across rebuilds.)

Distributing to others? See RELEASE.md for the Developer ID signing + notarization + appcast flow.

Shortcuts

Hold the activation modifier (⌘ by default) and:

Keys	Action
Tab / ⇧Tab	next / previous window
↑ ↓ (or ← →)	navigate the selection
1–9	jump straight to that window
Home / End	first / last window
P	pin / unpin the highlighted app
Q / W	quit the highlighted app (⌥ = force)
release the modifier	switch to the highlighted window
Esc	cancel
hover / click a row	highlight / switch with the mouse
menu bar → Switching Insights…	open the dashboard

Every extra key can be toggled off in Settings → Shortcuts.

Project layout

• Sources/PeekCore/ — pure, tested logic: SwitchEvent, StatsStore / PinStore (JSON persistence), StatsAggregator (per-day / top-apps / hourly / transitions), WindowRanker (affinity scoring + pin-aware ordering).
• Sources/Peek/ — the app: HotKey (CGEventTap), WindowLister (CGWindowList + ScreenCaptureKit thumbnails), SwitcherPanel (SwiftUI overlay), WindowActivator (exact-window raise via AX + _AXUIElementGetWindow), Dashboard (Swift Charts), SettingsWindow, Localize.
• Tests/PeekCoreTests/ — swift test covers ranking, aggregation, and persistence.
• CI builds + tests every PR (.github/workflows/ci.yml).

Requirements

macOS 14+ · Swift 6 toolchain · Apple Silicon or Intel. Built with Swift Package Manager (no Xcode project needed).

License

See LICENSE. Issues and PRs welcome — Peek is open source.