When choosing apps, many of us prefer ‘proper’ macOS apps, developed for the Mac platform, rather than hybrids using the likes of Electron or Catalyst. Although there are ways of detecting whether an app uses either of those, they’ve been fairly obscure and technical. I therefore welcome the free app 5 GUIs, now available from the App Store and as open source, which reveals (almost) all.

This app is named following a tweet from Joe Groff, one of Apple’s Swift team, saying ‘With its eclectic mix of AppKit, Catalyst, iOS, SwiftUI, and web apps, macOS should consider rebranding to “Five GUIs”’. Helge Heß of ZeeZide then built a “quick hack” using SwiftUI to create this app. Its source code is available from here, and the finished app for Catalina and Big Sur (only) is available as 5 GUIs from Apple’s App Store.

Although it currently doesn’t detect the use of Qt in an app, it should reveal whether any macOS app uses Electron, Catalyst, SwiftUI, AppKit, or is an iPhone app, and in many cases will also indicate the language used to code it.

If you’ve been wondering whether that app really does use Electron, this is the best way to find out. Thank you, Helge Heß, for an essential tool.