File Extension SIT
File extension SIT is most commonly associated with a StuffIt archive file. SIT files are similar to ZIP or RAR files in that they contain complete file and folder structures in a single, compressed archive. SIT files were originally used exclusively on the Apple platform, though Smith Micro StuffIt is now also available on the Windows platform. Though very uncommon, the SIT file extension may also be used to denote a Sinclair emulator snapshot, or PDP-10 Fortran-77 compiler source code file.
StuffIt was originally developed by Raymond Lau in 1987 to provide a one-step process for archiving and compressing files on Mac, and also offered an improved compression ratio over alternative utilities at the time. Though StuffIt was available as shareware or paid software, in order to make SIT files more widely compatible, a freeware decompression application called StuffIt Expander was released during the 1990's and has since become preloaded as part of the Mac operating system.
Though files on the Mac platform did not require file extensions, StuffIt archives used the SIT file extension so that archives could be stored on other platforms such as Windows and Linux. However, it is possible that the files contained with StuffIt archives contain characters in their names which are fine on the Mac but illegal in Windows, and this may prevent the file being extracted correctly on the latter platform.
SIT files can contain data of any kind, though are conventionally used for backup purposes, or to package files such as applications for distribution over the Internet. However, they could potentially contain malware, so should not be opened, particularly if they are from an unknown source, without checking the archive with an up to date virus scanner.
SIT files can be opened using Smith Micro StuffIt or StuffIt Expander on the Mac and Windows platforms. Archives created using the latest StuffIt X compression use the File extension SITX file extension.