In this Rocket Yard guide, we’ll look at how Gatekeeper operates, best use, and how to get around some of the restrictions Gatekeeper imposes. But sometimes, this tireless security system can get in the way of apps and extensions you need to run but don’t meet the sometimes strict requirements for getting past Gatekeeper. When Apple adds one of these to the list of known threats, your Mac will then block that version and you’ll need to download the latest one from its official source.Gatekeeper does its job quite well, standing guard and helping to keep your Mac safe. Other threats include versions of plug-ins, such as Adobe Flash Player, in which critical vulnerabilities have been discovered.

There’s a setting in the App Store pane in System Preferences that determines whether you receive updates that keep macOS’s knowledge of threats up to date.

When it detects a threat, macOS warns that the file you’re trying to open will damage your Mac and offers to trash it. Gatekeeper is backed up by another security measure whereby macOS receives details from Apple about known malware and implicit threats and blocks their ability to run. One of the most popular is HandBrake, a free tool that converts many video formats for iOS and other devices. Plenty of useful apps are blocked by Gatekeeper because their code hasn’t been signed by a registered developer. Should you avoid all such apps? Not necessarily, but you should exercise caution based on their source.

If you try to open an app that doesn’t meet your chosen security level, macOS will flash up a dialog that tells you so.

Mac gatekeeper settings