He was an early contributor to the free software movement. In 1986 he replaced John P. Nelson as editor of the original "moderated" Usenet group for free source code, mod.sources (later renamed to comp.sources.unix). This newsgroup was a primary distribution medium for high quality free software before Internet access became available to the public. He wrote cshar, which became the basis for sharutils.[discuss] Salz posted early releases of patch, localtime, perl, cvs, elm, and the first free tar program. He passed the job of editor to Paul Vixie in 1991. He also wrote InterNetNews, "the first available news server" and "the original software that most large news servers used" in Usenet. His select-based I/O architecture in INN has been replicated in high performance HTTP servers. Rich Salz was one of the authors of RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace.