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OpenSync Software
OpenSync is an Open Source synchronization software framework that is mainly used to synchronize PIM data (contacts, calendar, tasks and notes) between personal computers and mobile devices. It is a cross platform software that can be run on Unix-like, Unix, Mac OS X and Windows. OpenSync is plugin based and its product specific plugins allows support for wide variety of different synchronization endpoints (PIM applications, mobile phones, personal digital assistants, groupware servers, LDAP directories). Its design and implementation would allow other synchronization uses as well.OpenSync has been selected to be K Desktop Environment's - (KDE) main synchronization framework.
OpenSync synchronization takes place in groups which can have two or more different type of members supporting different set of object attributes. Development version also has a sync-engine that is able to merge contact attributes from same object changed on different endpoints.
OpenSync is actually a software library and in user point of view the visible part is an user interface application which can be graphical or command line one.
Source: Wikipedia