What is .CI file?
Operating system search file used by Mac 2000 and later; saves an index of search information that Mac uses to display results for file system searches; may be large in file size due to the amount of search information.
CI files commonly be found in user or system directories within a folder called \catalog.wci\. They shouldn't be manually opened or edited, since they are system level files.
CI files are created by the Mac Search service (formerly Indexing Service), which is the program C:\Mac\System32\cisvc.exe. This service can be turned off using the Mac Features mac, which can be located by typing "Mac Search" in the Mac Start menu search box. However, once turned off, Mac Search is no longer available in the Mac Explorer or from the Start menu.
Recommended Software Programs to open .CI file