StuffIt Expaner is a buyware, closed source data compression software utility developed by Allume Systems (formerly Aladdin Systems). There are freeware clients on some platforms than can do unpacking only. It runs in Mac OS Classic, Mac OS X, Microsoft Windows, and Linux x86/UNIX. It does not compress files. As of October 2007, the latest Macintosh version is 12.0, which requires Mac OS X v10.4. Version 10.0.2 runs on Mac OS X v10.3, and version 8.0.2 runs on Mac OS X v10.0-Mac OS X v10.2. The latest version for Mac OS 9 is 7.0.3. StuffIt has been a target of criticism and dissatisfaction from Mac users in the past as the file format changes frequently, notably during the introduction of StuffIt version 5.0. Expander 5.0 contained many bugs, and its file format was not readable by the earlier version 4.5, leaving Mac users of the time without a viable compression utility.