In 1995, Karl Fogel co-founded Cyclic Software, a company offering commercial CVS support. In 1999 he added support for CVS anonymous read-only repository access, inaugurating a new standard for access to development sources in open source projects. That same year, he wrote "Open Source Development With CVS" (published by Coriolis), now in its third edition via Paraglyph Press.
Since early 2000, he has worked for CollabNet, Inc, managing the creation and development of Subversion, a version control system written from scratch by CollabNet and a team of open source volunteers, and meant to replace CVS as the de facto standard among open source projects. He also participates in various other open source projects as a module maintainer, patch contributor, and documentation writer.