CVS is an open source program, and all the information necessary to interface to it or change it is freely available. It is also a very popular system. The combination of these two factors means that a wide variety of programs and tools have been written for CVS.
The tools in this appendix range from a port of CVS to the Windows NT operating system, to a small tool to mail log messages automatically. Other programs include several different viewers to display the contents of the repository with an HTTP server and a useful program that implements access-control lists.