How to open RAR files

  4. Legal stuff

  Unrar source may be used in any software to handle RAR archives

  without limitations free of charge, but cannot be used to re-create

  the RAR compression algorithm, which is proprietary. Distribution

  of modified Unrar source in separate form or as a part of other

  software is permitted, provided that it is clearly stated in

  the documentation and source comments that the code may not be used

  to develop a RAR (WinRAR) compatible archiver.