Download of CrushFTP5 5.80 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program lies within System Tools, more precisely File Compression. This free Mac app is a product of CrushFTP. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
CrushFTP is a powerful file server supporting standard secure file transfer protocols. The 'Crush' in CrushFTP comes from its ability to compress transfers on the fly seamlessly making for faster transfers! Combining the inline compression support with the high speed transfer options, you have the fastest file transfer options for high latency connections possible.
You may want to check out more software for Mac, such as CreaDMG, GeeUnRAR or Jarzilla, which might be similar to CrushFTP5.