Which macOS version was the last to support 32-bit applications?

macOS Mojave was the last macOS version to support 32-bit applications.

Mojave, also known as macOS 10.14, was released publicly on September 24, 2018. It preserved compatibility with older 32-bit Mac software while signaling that support was ending. When users opened a 32-bit app, Mojave displayed periodic warnings explaining that the application would not work with future versions of macOS.

The cutoff arrived with macOS Catalina 10.15 in 2019. Catalina could run only 64-bit applications, so older software stopped launching unless developers supplied an updated version or users retained Mojave. Apple’s shift reflected modern hardware and software priorities, including improved memory handling, security, and support for newer development frameworks.

High Sierra began warning users about 32-bit software, but it was not the final compatible release. Catalina is therefore the common wrong answer: it was the first version without 32-bit support, not the last version with it. Mojave also marked the end of several older technologies, including support for HFS+ startup disks without patching and Apple’s iPhoto application.