Why it's blocked
macOS quarantines anything you download from the internet. If the app isn't code-signed and notarized by its developer, Gatekeeper refuses to open it and shows "can't be opened because Apple cannot check it for malicious software." Nearly every slap app ships unsigned, so this is the #1 reason yours won't launch.
How to open a blocked slap app (safely)
- Right-click → Open. Control-click the app, choose Open, then click Open again in the dialog. This works for a one-off you trust.
- Privacy & Security. If that fails, open System Settings → Privacy & Security, find the "…was blocked" line, and click Open Anyway.
- The terminal command. Some apps tell you to run
xattr -cr /path/to/App.app to strip the quarantine flag. Only do this for an app you completely trust from its official source. Pasting terminal commands from random sites is exactly how people get burned.
Or don't do any of that. Slap Your Mac is signed with an Apple Developer ID and notarized by Apple, so it opens with a normal double-click. No right-click trick, no Privacy & Security detour, no terminal command. Download it and you're slapping in seconds.
Signed vs unsigned, in plain terms
"Notarized" means Apple has already scanned the app for malware and your Mac trusts it. "Unsigned" means it hasn't been through that, so macOS blocks it by default and makes you override the warning yourself. For a fun app you're installing on a whim, notarized is the version you want.
Frequently asked questions
Why won't my slap Mac app open?+
macOS quarantines apps downloaded from the internet. If the app isn't signed and notarized by its developer, Gatekeeper blocks it and shows a message like "can't be opened because Apple cannot check it for malicious software." Most slap apps ship unsigned, which is why you hit this.
How do I open a Mac app that's blocked by Gatekeeper?+
Right-click (or Control-click) the app, choose Open, then click Open again in the dialog. Or go to System Settings → Privacy & Security, find the "…was blocked" message, and click Open Anyway. Only do this for apps you trust.
Do I have to use Terminal to open a slap app?+
For most of them, effectively yes. Unsigned apps often need the right-click trick or a terminal command like xattr -cr to clear the quarantine flag. Slap Your Mac is notarized, so it just opens with a double-click, no terminal needed.
Is it safe to remove the quarantine flag?+
It's safe only if you completely trust the app and downloaded it from the official source. The quarantine flag exists to protect you, so bypassing it on a random download is risky. A notarized app never needs you to bypass anything.