CGoban (the name means "complete goban") is a free SGF editor and go client written by William Shubert. It is sometimes called "CGoban 1" to distinguish it from CGoban 2 and CGoban 3, which are different programs written later by the same author.
William Shubert no longer maintains CGoban. Its original web page is at http://www.igoweb.org/~wms/comp/cgoban/. The program now has new maintainers and a new web site at http://cgoban1.sourceforge.net/.