How to identify 32bit applications on macOS without running each one? With macOS 10.13.4 Apple will start to show a warning if a 32bit application is started, and it is assumed that with 10.14 32bit applications will not run at all. Starting each application to see whether it is 32bit might be cumbersome, so if I want to prepare for the migration early how can I easily (via GUI or Terminal) assemble a list of all 32bit applications on my system?
System Information uses the Spotlight index to find all applications accessible on the system.


Open the app (/Applications/Utilities/System Information.app
or Apple menu → About This Mac → System Report…).
Choose Applications under Software in the sidebar and wait for the data to load.
One of the columns present on this list is ‘64-Bit (Intel)’. 

Clicking on the column header sorts the column by the Yes/No values within.
Inspecting the apps listed as ‘No’ will tell you which apps are not 32-bit.




You can also use Spotlight's CLI tool, ‘mdfind’ (/usr/bin/mdfind) on the command line. Run the following in Terminal:

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


which returns paths to the application, such as:

/Applications/KeyBindingsEditor.app
/Applications/Impactor.app
/Applications/DVD Player.app
/Applications/Tuxera Disk Manager.app
/Applications/LICEcap.app
/Applications/Utilities/Adobe Flash Player Install Manager.app
/Applications/Compressor.app
/Applications/JPEGmini Pro.app


Currently in macOS 10.13, the following Apple first-party apps are 32-bit and still need updating or removing in 10.14:


/Applications/DVD Player.app
(probably being removed)
/System/Library/Input Methods/InkServer.app
(for the Ink support i.e. graphics tablets, probably being removed)
/System/Library/Frameworks/QuickLook.framework/Versions/A/Resources/quicklookd32.app
(a 64-bit version already exists, quicklookd.app without the 32 in the name)