CoSy was an early computer conferencing system developed by the University of Guelph in 1983 and 1984. CoSy was selected by Byte Magazine to launch their BIX system in 1985
In addition to BIX, it was used to implement a similar British system named CIX, as well as numerous other installations such as CompuLink Network. CoSy was also chosen for The Open University's "electronic campus".
Some rights to the software were later acquired by the British Columbia company SoftWords, who developed it into CoSy400 and added a simple web interface, before losing interest.
When the BIX system closed down, several former "bixen" approached University of Guelph and SoftWords and obtained the right to release the original version of CoSy under the GPL. It is now developed as an open source project, and is the basis of the BIX-like NLZero (Noise Level Zero) conferencing service.