I need a zip file (ZIP64) for a test case, I put a bigfile of 5GB full of zeros and zipped it, but I don't know if is ZIP64.

Should the ZIP file exceed 4Gb to be ZIP64? A 4Gb file for a test case is pretty twisted can I have another option?

  • Are you just after some way to confirm that the zip you create is actually a 64bit instead of a 32bit zip? – Dave Sep 11 '12 at 13:05
  • @DaveRook yes but I think they are not called 64bit and 32bit, just orginal zip format and ZIP64. – Eduard Florinescu Sep 11 '12 at 13:42
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    Googling matched this python3 script. It worked for me. – gman Sep 23 '19 at 17:51

Download the DotNetZip devkit from http://dotnetzip.codeplex.com/. Extract the Tools folder from the dev kit and run DotNetZip-WinFormsTool.exe

It has a ZIP64 setting with the options:

  • Always
  • AsNecessary
  • Never

Select the Always option to create archives in the ZIP64 format even if they only contain small files. The interface is a little clunky, but it's workable; it allowed me to create the ZIP64 test cases I needed.


The archival tool 7zip supports zip64 archives. You could use that to generate your test case or validate it.

  • 7-zip.org/history.txt - 7-Zip now supports Zip64 extension of ZIP format. So now it's possible to compress files bigger than 4 GB to ZIP archives. - 'zip' is just the container, 'deflate64' is the actual compression scheme used by a zip64 file. – PhonicUK Sep 11 '12 at 9:50
  • 7zip supports deflate64 and also zip64. – Eduard Florinescu Sep 11 '12 at 9:51
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    I don't find a way to test if a zip64 with 7zip – Eduard Florinescu Sep 11 '12 at 9:53
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    I was able to determine if my Zip was Zip64 in 7-Zip by looking at the Characteristics column of the zip entries: i.stack.imgur.com/Cb6ZX.jpg – Sal Aug 21 '18 at 14:01

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