I shipped a clipboard manager inside the macOS App Store sandbox. Here's what works and what doesn't.

Eduardo Revilla Vaquero — Thu, 06 Aug 2026 17:26:28 +0000

I've used clipboard managers on the Mac for about a decade, and they all stop in the same place: they remember everything and do nothing with it. I'd copy a minified JSON blob and paste it into an editor just to format it. Copy a variable name and retype it in snake_case. Copy a screenshot of an error and go hunting for an OCR tool. The history was never the bottleneck. The round trip to another app was.

So I built ClipMason, a clipboard manager that acts on what you copy instead of just storing it. The features aren't the interesting part for this crowd, though. The interesting part was staying inside the Mac App Store sandbox, because most of the well-known managers ship outside it or lean on the Accessibility API. I wanted to know what you can actually do without either.

Here are the notes.

What works fine in the sandbox

NSPasteboard monitoring. There is no notification API for the pasteboard, so it is a 0.5s Timer polling changeCount. Idle cost is negligible; I measured it before shipping and it never showed up.

Global hotkeys via Carbon RegisterEventHotKey (⌘⇧V). No Input Monitoring prompt, no Accessibility prompt. This surprised me. A lot of people assume a global shortcut forces you out of the sandbox, and it doesn't.

Vision for OCR. VNRecognizeTextRequest with .accurate is a system framework, works entitlement-free, and it was good enough that I never bothered writing a fallback.

SwiftData for storage, with @Attribute(.externalStorage) on the image blobs so the database doesn't balloon.

MenuBarExtra plus a Window scene plus a Settings scene, with LSUIElement = true so there is no Dock icon.

NSWorkspace.frontmostApplication for attributing each clip to the app it came from.

What doesn't

Auto-paste into the frontmost app. That needs the Accessibility API (AXUIElement) or posting CGEvents into another process. Both are out in the sandbox. So ⌘⇧V puts the clip on the pasteboard and you press ⌘V yourself. This is the one real UX cost, and I would rather say it plainly than pretend it isn't there. If auto-paste is a dealbreaker for you, an Accessibility-based manager is the right call.

Reading other apps' state beyond what NSWorkspace exposes. Not available, by design.

The privacy bit worth stealing

org.nspasteboard.ConcealedType is a community convention, not an Apple API. Password managers set it on the pasteboard when they copy a secret. Checking for it is three lines and means passwords never enter your history:

let concealed = NSPasteboard.PasteboardType(rawValue: "org.nspasteboard.ConcealedType")
if pasteboard.data(forType: concealed) != nil { return }

If you are building anything that touches NSPasteboard, please implement this. It is the difference between a clipboard history and a password leak.

Architecture

Roughly: models (SwiftData) / services (ClipboardMonitor, HotkeyManager, OCRService, SmartTagDetector, PrivacyManager) / views split by surface (menu bar, popup, main window, actions, settings).

The one decision that paid off: actions are enums with an execute(_:) method. TextAction has 23 cases (case conversions, URL/Base64, JSON pretty-print and minify, hashes, line ops, counts), ImageAction has 14 (OCR, rotate, flip, resize, annotate, export). Adding a transformation is one case, and localization falls out of the enum almost for free.

About 4,700 lines of Swift, a 2.9 MB shipped binary, 17 languages through String Catalogs, and no network code at all. Grep the binary for URLSession and you get nothing, which is exactly what a clipboard manager should be.

If you want to see it

ClipMason is on the Mac App Store for $6.99, one time, no subscription. macOS 14+.

Mostly, though, I am curious what other sandbox edges people have run into. If you have shipped something that had to stay inside the App Store and found a workaround, or a wall, I would like to hear it.

I built a clipboard manager for macOS that replaces 5 different tools

Eduardo Revilla Vaquero — Wed, 04 Mar 2026 12:17:33 +0000

As a developer I was tired of switching between tools every time I needed to process something I copied. Format JSON? Open a website. Encode Base64? Another tab. Resize an image? Open Preview. Convert a hex color? Google it. So I built ClipMason, a clipboard manager for macOS that detects what you copy and offers contextual actions right there.

How it works

ClipMason lives in the menu bar. Every time you copy something, it detects the content type and shows relevant actions.

Text (22+ actions)

Case conversion: uppercase, lowercase, Title Case, camelCase, snake_case, kebab-case

Encoding: Base64, URL encode/decode

Formatting: JSON pretty print, JSON minify

Hashing: MD5, SHA-256

Lines: sort A-Z/Z-A, remove duplicates, remove blank lines

Stats: character, word, and line count

Images

Resize with precise control (percentage or exact pixel dimensions)

Rotate, flip, grayscale, invert colors

Annotate with drawings

Extract text with OCR

Export as PNG or JPEG

Colors
Copy a hex string like #FF5733? ClipMason detects it automatically and lets you convert to HEX, RGB, HSL, SwiftUI Color or CSS format.

URLs

Open in browser

Extract domain

Convert to Markdown link

Files

Open with default app

Reveal in Finder

Copy path for terminal use

Tech stack

SwiftUI for the UI, SwiftData for persistence, Swift 6 with strict concurrency. macOS 14+ native app, no Electron. 16 languages supported. Everything runs locally. No cloud, no tracking, no subscription.

What I learned building it

The hardest part was clipboard type detection. macOS puts multiple representations on the pasteboard simultaneously—for example, copying a file also puts a PNG icon on the clipboard. Getting the detection order right was tricky.

Another challenge was image resizing on Retina displays. Using lockFocus() creates a 2x backing store, so a 100x100 resize produced 200x200. Switching to explicit NSBitmapImageRep with pixel dimensions fixed it.

ClipMason is available on the Mac App Store as a one-time purchase. I'd love to hear what actions you'd find useful—I'm actively adding features based on feedback.