Guide

Apple could not verify an app is free of malware: what it means

Last updated: October 25, 2026

You download an app, open it, and macOS says: "Apple could not verify '[app]' is free of malware that may harm your Mac or compromise your privacy." Older versions of macOS put it as "can't be opened because Apple cannot check it for malicious software". It sounds alarming. This guide explains what it really means, how to tell whether a download is safe, and how to open the app if it is.

What the warning means

macOS has a feature called Gatekeeper that checks apps downloaded from the internet. Apps from the App Store, and apps whose developer paid for Apple's Developer Program and sent the app to Apple for an automated scan (called notarization), open without a prompt.

When an app hasn't been through that, macOS can't check it, so it shows this warning and blocks it until you decide. So the warning tells you macOS couldn't check the app, and nothing more. Small developers, open-source projects and new apps often aren't notarized because of the yearly fee and the paperwork.

Is it safe to open?

Where the app came from tells you more than the warning does. Before you open it, ask:

Did it come from the developer's own website or their official GitHub page, rather than a download site, a forum post or a link in a message?
Is the developer real and reachable? A website with contact details, policies and a support address is a good sign.
Does the file match? If the developer publishes a checksum, compare it (below).

If you can't answer yes, don't open it. Move it to the Trash.

Check the download with a checksum

A checksum is a fingerprint of a file. If even one byte changes, the fingerprint changes. Developers who publish one let you prove your copy is the one they released.

Open Terminal (Applications → Utilities).
Type shasum -a 256 with a space, then drag the downloaded file into the window and press Return.
Compare the long code it prints with the one on the developer's website. They must match exactly.

How to open the app (macOS 15 Sequoia and later)

Open the app once. When the warning appears, click Done. Don't click Move to Trash.
Open System Settings → Privacy & Security.
Scroll down to Security. You'll see a line saying the app was blocked. Click Open Anyway.
Confirm with your password or Touch ID, then click Open.

The Open Anyway button only stays for about an hour after macOS blocks the app. If you don't see it, open the app again, click Done, and go straight back to Privacy & Security.

From then on the app opens normally. You only do this once per app, though an update to the app may ask again.

On macOS 14 Sonoma and earlier, there's a shortcut: Control-click the app in Finder, choose Open, then click Open in the dialog. Apple removed that shortcut in macOS 15.

Don't switch off Gatekeeper

Some guides tell you to run a Terminal command that turns off Gatekeeper for every app. Don't. It removes the check for everything you download afterwards. Open Anyway allows just the one app you've decided to trust.

Why PC Game Port shows this warning

PC Game Port isn't notarized by Apple yet, so macOS shows this warning the first time you open it. To check your copy:

Download it only from pcgameport.com, which links to our official GitHub releases.
The checksum of the current .dmg is in the Terminal window on the home page, so you can check your copy.
The one-line Terminal install skips the warning: it puts the app in the Applications folder inside your home folder, and needs no admin password.

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