By the fall of 1987 StuffIt had largely replaced PackIt in the Mac world, with many software sites even going so far as to convert existing PackIt archives to save more space. Compared to existing utilities on the Mac, notably PackIt, StuffIt offered 'one step' operation and higher compression ratios. It combined the fork-combining capabilities of utilities such as MacBinary with newer compression algorithms similar to those used in ZIP. StuffIt was originally developed in the summer of 1987 by Raymond Lau, who was then a student at Stuyvesant High School in New York City.
Raymond Lau (creator), currently Smith Micro
SIT!, SITD, SIT2, SIT5 (depending on file version)