A device for cleaving optical fibers having a housing with an internal chamber, a fiber alignment member removably connected to the housing and a fiber cutting member supported by the housing. The alignment member has an opening sized to receive the ferrule of a fiber optic connector and has a stop proximate to the inward end of an opening to engaged the ferrule distal end. The alignment member is quickly interchangeable with another sized and arranged to handle the ferrule of a different type or size connector. The opening is sized to receive ferrule with an optical fiber to be cleaved, and permits the fiber to extend inward beyond the inward end of the opening and into the housing internal chamber. The fiber cutting member is mounted to the housing to cleave the fiber inserted into the opening and cause separation of a cut end of the fiber within the housing internal chamber, and is quickly removable for replacement when the alignment member is disconnected from the housing if a blade thereof is damaged or worn. The alignment member has a user operable lock to unlock the alignment member from the housing. The lock has a release positioned within the housing internal chamber for access by a user through a housing opening sized to provide access to the housing internal chamber. An endcap closes the housing opening and hold a spare fiber cutting member.