The zlib License is a permissive free software license which defines the terms under which the zlib

Zlib

zlib is a software library used for data compression. zlib was written by Jean-Loup Gailly and Mark Adler and is an abstraction of the DEFLATE compression algorithm used in their gzip file compression program. Zlib is also a crucial component of many software platforms including Linux, Mac OS X,...

 and libpng

Libpng

libpng is the official Portable Network Graphics reference library . It is a platform-independent library that contains C functions for handling PNG images...

 software libraries can be distributed. It is also used by other free software

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 packages.

The zlib License has been approved by the Free Software Foundation

Free Software Foundation

The Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to create, distribute and modify computer software...

 (FSF) as a free software licence

Free software licence

A free software licence is a software licence which grants recipients rights to modify and redistribute the software, which would otherwise be prohibited by copyright law. A free software licence grants, to the recipients, freedoms in the form of permissions to modify or distribute copyrighted work...

, and by the Open Source Initiative

Open Source Initiative

The Open Source Initiative is an organization dedicated to promoting open source software.The organization was founded in February 1998, by Bruce Perens and Eric S. Raymond, prompted by Netscape Communications Corporation publishing the source code for its flagship Netscape Communicator product...

 (OSI) as an open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 license. It is compatible

License compatibility

License compatibility refers to the problem with licenses applied to works subject to copyright, particularly licenses of software packages, which can contain contradictory requirements, rendering it impossible to combine source code from such packages or content from such works in order to create...

 with the GNU General Public License

GNU General Public License

The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....

.

Terms

The license only has the following points to be accounted for:

• Software is used on 'as-is' basis. Authors are not liable for any damages arising from its use.
• The distribution of a modified version of the software is subject to the following restrictions:
  1. The authorship of the original software must not be misrepresented,
  2. Altered source versions must not be misrepresented as being the original software, and
  3. The license notice must not be removed from source distributions.

The license does not require source code

Source code

In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...

to be made available if distributing binary code.

Text

The license terms are as follows:

Copyright (c) <year> <copyright holders>



This software is provided 'as-is', without any express or implied

warranty. In no event will the authors be held liable for any damages

arising from the use of 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 following restrictions:



   1. The origin of this software must not be misrepresented; you must not

   claim that you wrote the original software. If you use this software

   in a product, an acknowledgment in the product documentation would be

   appreciated but is not required.



   2. Altered source versions must be plainly marked as such, and must not be

   misrepresented as being the original software.



   3. This notice may not be removed or altered from any source

   distribution.

External links

• License text on the zlib homepage