Export or archive contacts in Contacts on Mac
Import contacts into Contacts on Mac
vCard Editor Trial is a signed application by the develope ID, and a sandbox application.
An application which is not signed is blocked for installing by a Gatekeeper.
The Gatekeeper is a secrity feature introduced from Mac OS X 10.7.5 Lion to help protect your Mac from malware and misbehaving apps downloaded from the Internet.
vCard Editor2 and vCard Editor2 Trial are sandbox applications too. It is prohibited by the sandbox to access to the Internet.