How to Find All 32-Bit Apps on a Mac
MacOS High Sierra is the last macOS release to support 32-bit apps “without compromise” (presumably meaning without performance degradation, and with maximum compatibility), and betas of macOS 10.13.4 are now notifying users if 32-bit apps are being run. This might suggest that 32-bit Mac apps will run through a compatibility mode like Rosetta or Classic in the near future, and eventually, it seems likely that Apple will drop support for 32-bit apps on the Mac completely in a some future system software release, favoring 64-bit apps.
But there are a fair amount of 32-bit apps which are widely used on many Macs, despite Mac OS itself being 64-bit since Snow Leopard. If you’re not sure what apps are 32-bit or 64-bit, then you’ll be glad to know that Mac OS has a handy tool available within System Information to quickly show you all the apps which are 64-bit or not.