In December 1999, with the release of Zip 2.3, Info-ZIP switched from its old, ad hoc license (embodied in the COPYING file) to a new, more standard version based on the BSD license. Here is the text of the new license, which applies to all source files in Zip 2.3 and later, UnZip 5.41 and later, WiZ 5.0 and later, and MacZip 1.05 and later, except where explicitly stated otherwise:

This is version 2009-Jan-02 of the Info-ZIP license. The definitive version of this document should be available at indefinitely and a copy at

Copyright (c) 1990-2009 Info-ZIP. All rights reserved.

For the purposes of this copyright and license, "Info-ZIP" is defined as the following set of individuals:

Mark Adler, John Bush, Karl Davis, Harald Denker, Jean-Michel Dubois, Jean-loup Gailly, Hunter Goatley, Ed Gordon, Ian Gorman, Chris Herborth, Dirk Haase, Greg Hartwig, Robert Heath, Jonathan Hudson, Paul Kienitz, David Kirschbaum, Johnny Lee, Onno van der Linden, Igor Mandrichenko, Steve P. Miller, Sergio Monesi, Keith Owens, George Petrov, Greg Roelofs, Kai Uwe Rommel, Steve Salisbury, Dave Smith, Steven M. Schweda, Christian Spieler, Cosmin Truta, Antoine Verheijen, Paul von Behren, Rich Wales, Mike White.

This software is provided "as is," without warranty of any kind, express or implied. In no event shall Info-ZIP or its contributors be held liable for any direct, indirect, incidental, special or consequential damages arising out of the use of or inability to use this software.

Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the above disclaimer and the following restrictions:

  1. Redistributions of source code (in whole or in part) must retain the above copyright notice, definition, disclaimer, and this list of conditions.

  2. Redistributions in binary form (compiled executables and libraries) must reproduce the above copyright notice, definition, disclaimer, and this list of conditions in documentation and/or other materials provided with the distribution. Additional documentation is not needed for executables where a command line license option provides these and a note regarding this option is in the executable's startup banner. The sole exception to this condition is redistribution of a standard UnZipSFX binary (including SFXWiz) as part of a self-extracting archive; that is permitted without inclusion of this license, as long as the normal SFX banner has not been removed from the binary or disabled.

  3. Altered versions--including, but not limited to, ports to new operating systems, existing ports with new graphical interfaces, versions with modified or added functionality, and dynamic, shared, or static library versions not from Info-ZIP--must be plainly marked as such and must not be misrepresented as being the original source or, if binaries, compiled from the original source. Such altered versions also must not be misrepresented as being Info-ZIP releases--including, but not limited to, labeling of the altered versions with the names "Info-ZIP" (or any variation thereof, including, but not limited to, different capitalizations), "Pocket UnZip," "WiZ" or "MacZip" without the explicit permission of Info-ZIP. Such altered versions are further prohibited from misrepresentative use of the Zip-Bugs or Info-ZIP e-mail addresses or the Info-ZIP URL(s), such as to imply Info-ZIP will provide support for the altered versions.

  4. Info-ZIP retains the right to use the names "Info-ZIP," "Zip," "UnZip," "UnZipSFX," "WiZ," "Pocket UnZip," "Pocket Zip," and "MacZip" for its own source and binary releases.

This license is also available as plain ASCII:

The text in the LICENSE file should be identical to that above except for the absence of HTML markup (obviously). But in case of discrepancies in the actual wording, is the definitive version.

Note that the lack of the BSD ``advertising clause'' and the presence of the third and fourth restrictions are the two principal differences from the BSD license. Restriction #3 is intended only to protect us from having to support other people's code and from getting blamed for other people's bugs. (We have enough bugs of our own. :-) )


Here are some examples of what we consider acceptable and unacceptable (i.e., misrepresentative) uses of the Info-ZIP names and contact info:

This is a port of Info-ZIP's Zip to the FooBar 9000 by JoeBob JBobberson. I have submitted my patches to Info-ZIP, so the port should be incorporated into the next official release. This is the official FooBar 9000 port of Info-ZIP's Zip.
The original UnZip sources are available from Info-ZIP's home site at ; my patches are available from Send any bug reports on the FooBar 9000 port to . (complete absence of identifying material or contact information other than that included in standard Info-ZIP documentation or source code)
at top of the screen displayed by typing ``unzip'' with no parameters:
UnZip 5.40 of 28 November 1998, by Info-ZIP. FooBar 9000 port maintained by JoeBob JBobberson; send bug reports to UnZip 5.40 of 28 November 1998, by Info-ZIP. Maintained by C. Spieler. Send bug reports to the authors at; see README for details.

With regard to what defines a ``port'' (i.e., sufficiently different from ``our code'' that we would like you to be the first line of defense against bug reports), the usual rule of thumb is: if you didn't have to change any source code, it's not a new port. This includes cases where maybe you had to supply some unusual compiler flags (unless they have to do with aggressive optimizations that may fail unpredictably) or define a macro that isn't present in the standard makefile(s); we'd love to hear from you so that such things can be incorporated into future makefiles, but they don't constitute a port. The prototypical example is a new Unix variant, perhaps where it was necessary to compile via make -f unix/Makefile LOCAL_UNZIP="-DNO_UID_GID -DZMEM" all or something similar, but more typically where it wasn't necessary to do anything special.

Self-extracting Archives

As noted in condition #2, Info-ZIP's self-extractor stub, UnZipSFX, and its variants (such as SFXWiz) constitute a special case. Redistribution of those as part of a self-extracting archive, without the inclusion of the Info-ZIP license in accompanying documentation, is allowed as long as the normal SFX banner has not been removed or disabled. Note that the banner text may be extended, however. For example, it is completely acceptable (and desirable!) to append to the UnZipSFX banner a notice such as:

This archive is being distributed by XYZfoo Corporation. See for contact information and other help.


The license given above covers only Info-ZIP's code. There are five files in the Zip and UnZip distributions that are covered by separate copyrights and licenses:

mktime.c is copyrighted by David MacKenzie and Michael Haertel and may be used freely as long as its copyright notice is retained and functional changes are noted. (In other words, its license is roughly equivalent to the Info-ZIP license.)

The full version of unreduce.c is the only remaining trace of Samuel H. Smith's original 1989 code, and its license explicitly prohibits commercial use and requires distribution of source code if the code is used in another program; as of UnZip 5.42, it is provided only as a separate add-on, not as part of the main UnZip distribution. (The stub version included with UnZip 5.42 and later is merely a placeholder and does not contain any of Smith's code.)

time_lib.c is copyrighted by Norbert Pueschel and may not be used commercially without the explicit permission of the copyright holder; non-commercial distribution by anyone other than Info-ZIP requires the inclusion of an additional piece of documentation.

macstuff.c and macstuff.h are derived from the More Files package and are copyrighted by Apple Computer and Jim Luther. They may be used without restriction provided that the source code is documented as having descended from Apple Sample Code and as containing subsequent changes. See the comments in the relevant source files for details.

In addition, versions of the following files that were released prior to this license were (and always will be) in the public domain. Newer versions are now covered by our copyright and license, but that doesn't affect the older copies:

Finally, note that the copyright and license presented here do not give you any special rights with respect to patents, export regulations, trademarks, or other laws of the United States or other countries. This may or may not be an issue for the code in unshrink.c, crypt.c, crypt.h, etc.

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