2018 Platform State of the Union
2018 Platform State of the Union

During the Platform State of the Union at WWDC 2018 Apple confirmed that macOS Mojave (10.14.x) will be the last version of macOS to run 32-bit code.

system_profiler

This one-liner is courtesy of @MacLemon.

system_profiler SPApplicationsDataType \
    | grep -E '^    .*:$|64-Bit \(Intel\):|Location' \
    | grep -A1 ': No' \
    | grep 'Location' \
    | sed -e 's/.*Location: //' 

On my system this command finds:

/System/Library/Input Methods/InkServer.app
/System/Library/Frameworks/QuickLook.framework/Versions/A/Resources/quicklookd32.app

Spotlight (mdfind)

Rich Trouton recommends using Spotlight.

mdfind "kMDItemExecutableArchitectures == '*i386*' && kMDItemExecutableArchitectures != '*x86*'"

This finds significantly more 32-bit code:

/System/Library/Input Methods/InkServer.app
/System/Library/Frameworks/QuickLook.framework/Versions/A/Resources/quicklookd32.app
...
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/Metadata.framework/Versions/A/Support/libmdworker.dylib
/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/NavigationServices.framework/Versions/A/NavigationServices
...
/System/Library/PrivateFrameworks/CoreMediaIOServicesPrivate.framework/Versions/A/CoreMediaIOServicesPrivate
/System/Library/Printers/Libraries/libConverter.dylib

Base on my limited testing I’d advise following Rich’s recommendation, use mdfind to find 32-bit code.

Dachshund photo by Carissa Weiser on Unsplash
Photo by Carissa Weiser on Unsplash