Greypaint, One Updater for Every Mac App

Field notes

Greypaint compares installed apps with four possible update sources: Sparkle appcasts, Homebrew casks, GitHub releases, and the Mac App Store. The page gives concrete sample version changes and says comparisons happen on the Mac, with zero sign-ins, zero telemetry events, and zero uploaded bytes. App Store updates remain subject to Apple's interface, while installer packages may trigger the normal macOS administrator prompt.