Andrew Tridgell and Paul Mackerras wrote the original rsync, which was first announced on 19 June 1996. Tridgell discusses the design, implementation, and performance of rsync in chapters 3 through 5 of his Ph.D. thesis in 1999. It is currently maintained by Wayne Davison.
Because of the flexibility, speed, and scriptability of rsync, it has become a standard Linux utility, included in all popular Linux distributions.