Open an app from an unidentified developer

Allow a trusted application that macOS refuses to open.

1. First try right-click on the application → Open, then confirm.
2. Otherwise: System Settings → Privacy & Security, scroll to the message about the blocked application and click "Open Anyway".
3. As a last resort, remove the quarantine attribute from an application you have verified:

   xattr -d com.apple.quarantine /Applications/MonApp.app

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4. Always download software from the publisher's official website.