Gatekeeper, first introduced in OS X Mountain Lion, is a Mac security feature which prevents the user from launching potentially harmful applications. In macOS Sierra, however, Apple made some important changes to Gatekeeper that seemingly limit the choices of power users. But don’t worry, Gatekeeper can still be disabled in Sierra. Here’s how.
Traditionally, Gatekeeper offered three settings of increasing security: anywhere, App Store and identified developers, and App Store only. The first choice, as its name describes, allowed users to launch applications from any source, effectively disabling the Gatekeeper feature. The second choice allowed users to run apps from the Mac App Store as well as from software developers who have registered with Apple and securely sign their applications. Finally, the most secure setting limited users to running apps obtained from the Mac App Store only.
While the secure options were good ideas for less experienced Mac users, power users found Gatekeeper to be too limiting and typically sought to disable it by setting it to “Anywhere.” In macOS Sierra, however, the “Anywhere” option is gone, leaving “App Store” and “App Store and identified developers” as the only two options.