At WWDC 2017, we announced new apps submitted to the Mac App Store must support 64-bit starting January 2018, and Mac app updates and existing apps must support 64-bit starting June 2018. If you distribute your apps outside the Mac App Store, we highly recommend distributing 64-bit binaries to make sure your users can continue to run your apps on future versions of macOS. macOS High Sierra will be the last macOS release to support 32-bit apps without compromise.

Learn more about distributing Mac apps.