Google Contacts, Free Address Book, Contacts+ , vCard Studio, CircleBack, es-Builder, Open Contacts, Contact PEA, Microsoft People, Microsoft Entourage, Contactizer Pro, E-Z Contact Book, GNOME Contacts, Covve Personal CRM, Google Sync, Windows Contacts, uBusinessDirectory, Relationship, Addza, OLFolderSync, OsaSync, ContactBase, Contacts Express are some alternatives to Kontact - KAddressBook.