The Open Source Definition

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The Open Source Definition is a document published by the Open Source Initiative, to determine whether a software license can be labeled with the open-source certification mark. [1]


The definition was taken from the exact text of the Debian Free Software Guidelines, written and adapted primarily by Bruce Perens [2] with input from the Debian developers on a private Debian mailing list. The document was created 9 months before the formation of the Open Source Initiative.


Open source doesn't just mean access to the source code. The distribution terms of open-source software must comply with the following criteria:

  1. Free redistribution: The license shall not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license shall not require a royalty or other fee for such sale.
  2. Source code: The program must include source code, and must allow distribution in source code as well as compiled form. Where some form of a product is not distributed with source code, there must be a well-publicized means of obtaining the source code for no more than a reasonable reproduction cost preferably, downloading via the Internet without charge. The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated source code is not allowed. Intermediate forms such as the output of a preprocessor or translator are not allowed.
  3. Derived works: The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software.
  4. Integrity of the author's source code: The license may restrict source-code from being distributed in modified form only if the license allows the distribution of "patch files" with the source code for the purpose of modifying the program at build time. The license must explicitly permit distribution of software built from modified source code. The license may require derived works to carry a different name or version number from the original software.
  5. No discrimination against persons or groups: The license must not discriminate against any person or group of persons.
  6. No discrimination against fields of endeavor: The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.
  7. Distribution of license: The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties.
  8. License must not be specific to a product: The rights attached to the program must not depend on the program's being part of a particular software distribution. If the program is extracted from that distribution and used or distributed within the terms of the program's license, all parties to whom the program is redistributed should have the same rights as those that are granted in conjunction with the original software distribution.
  9. License must not restrict other software: The license must not place restrictions on other software that is distributed along with the licensed software. For example, the license must not insist that all other programs distributed on the same medium must be open-source software.
  10. License must be technology-neutral: No provision of the license may be predicated on any individual technology or style of interface.


FSF position

The open source movement's definition of open source software by the Open Source Initiative and the official definitions of free software by the Free Software Foundation (FSF) basically refer to the same software licenses (with a few minor exceptions see Comparison of free and open-source software licenses), both definitions stand therefore for the same qualities and values. [2] Despite that, FSF founder Richard Stallman stresses underlying philosophical differences when he comments:

The term “open source” software is used by some people to mean more or less the same category as free software. It is not exactly the same class of software: they accept some licences that we consider too restrictive, and there are free software licences they have not accepted. However, the differences in extension of the category are small: nearly all free software is open source, and nearly all open source software is free.

Free Software Foundation [3]

Open Knowledge

Open Knowledge International (OKI) [4] described in their Open Definition for open content, open data, and open licenses, "open/free" as synonymous in the definitions of open/free in the Open Source Definition, the FSF and the Definition of Free Cultural Works:

This essential meaning matches that of "open" with respect to software as in the Open Source Definition and is synonymous with “free” or “libre” as in the Free Software Definition and Definition of Free Cultural Works.

The Open Definition [5]

See also

Related Research Articles

<span class="mw-page-title-main">Bruce Perens</span>

Bruce Perens is an American computer programmer and advocate in the free software movement. He created The Open Source Definition and published the first formal announcement and manifesto of open source. He co-founded the Open Source Initiative (OSI) with Eric S. Raymond. Today, he is a partner at OSS Capital.

<span class="mw-page-title-main">Free software</span> Software licensed to preserve user freedoms

Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, not price; all users are legally free to do what they want with their copies of a free software regardless of how much is paid to obtain the program. Computer programs are deemed "free" if they give end-users ultimate control over the software and, subsequently, over their devices.

The Free Software Definition written by Richard Stallman and published by the Free Software Foundation (FSF), defines free software as being software that ensures that the end users have freedom in using, studying, sharing and modifying that software. The term "free" is used in the sense of "free speech," not of "free of charge." The earliest-known publication of the definition was in the February 1986 edition of the now-discontinued GNU's Bulletin publication by the FSF. The canonical source for the document is in the philosophy section of the GNU Project website. As of April 2008, it is published in 39 languages. The FSF publishes a list of licences which meet this definition.

<span class="mw-page-title-main">GNU</span> Free software collection

GNU is an extensive collection of free software, which can be used as an operating system or can be used in parts with other operating systems. The use of the completed GNU tools led to the family of operating systems popularly known as Linux. Most of GNU is licensed under the GNU Project's own General Public License (GPL).

<span class="mw-page-title-main">GNU Lesser General Public License</span> Free-software license

The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own software without being required by the terms of a strong copyleft license to release the source code of their own components. However, any developer who modifies an LGPL-covered component is required to make their modified version available under the same LGPL license. For proprietary software, code under the LGPL is usually used in the form of a shared library, so that there is a clear separation between the proprietary and LGPL components. The LGPL is primarily used for software libraries, although it is also used by some stand-alone applications.

An open-source license is a type of license for computer software and other products that allows the source code, blueprint or design to be used, modified and/or shared under defined terms and conditions. This allows end users and commercial companies to review and modify the source code, blueprint or design for their own customization, curiosity or troubleshooting needs. Open-source licensed software is mostly available free of charge, though this does not necessarily have to be the case.

<span class="mw-page-title-main">Open Source Initiative</span> Non-profit organization promoting open-source software

The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation, with 501(c)(3) tax-exempt status.

The Open Software License (OSL) is a software license created by Lawrence Rosen. The Open Source Initiative (OSI) has certified it as an open-source license, but the Debian project judged version 1.1 to be incompatible with the DFSG. The OSL is a copyleft license, with a termination clause triggered by filing a lawsuit alleging patent infringement.

<span class="mw-page-title-main">Open-source software</span> Software licensed to ensure source code usage rights

Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration, meaning any capable user is able to participate online in development, making the number of possible contributors indefinite. The ability to examine the code facilitates public trust in the software.

The Debian Free Software Guidelines (DFSG) is a set of guidelines that the Debian Project uses to determine whether a software license is a free software license, which in turn is used to determine whether a piece of software can be included in Debian. The DFSG is part of the Debian Social Contract.

<span class="mw-page-title-main">Free and open-source software</span> Software whose source code is available and which is permissively licensed

Free and open-source software (FOSS) is a term used to refer to groups of software consisting of both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the source code is openly shared so that people are encouraged to voluntarily improve the design of the software. This is in contrast to proprietary software, where the software is under restrictive copyright licensing and the source code is usually hidden from the users.

Alternative terms for free software, such as open source, FOSS, and FLOSS, have been a controversial issue among free and open-source software users from the late 1990s onwards. These terms share almost identical licence criteria and development practices.

This comparison only covers software licenses which have a linked Wikipedia article for details and which are approved by at least one of the following expert groups: the Free Software Foundation, the Open Source Initiative, the Debian Project and the Fedora Project. For a list of licenses not specifically intended for software, see List of free-content licences.

License compatibility is a legal framework that allows for pieces of software with different software licenses to be distributed together. The need for such a framework arises because the different licenses can contain contradictory requirements, rendering it impossible to legally combine source code from separately-licensed software in order to create and publish a new program. Proprietary licenses are generally program-specific and incompatible; authors must negotiate to combine code. Copyleft licenses are commonly deliberately incompatible with proprietary licenses, in order to prevent copyleft software from being re-licensed under a proprietary license, turning it into proprietary software. Many copyleft licenses explicitly allow relicensing under some other copyleft licenses. Permissive licenses are compatible with everything, including proprietary licenses; there is thus no guarantee that all derived works will remain under a permissive license.

The following outline is provided as an overview of and topical guide to free software and the free software movement:

<span class="mw-page-title-main">Free-software license</span> License allowing software modification and redistribution

A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and redistribute that software. These actions are usually prohibited by copyright law, but the rights-holder of a piece of software can remove these restrictions by accompanying the software with a software license which grants the recipient these rights. Software using such a license is free software as conferred by the copyright holder. Free-software licenses are applied to software in source code and also binary object-code form, as the copyright law recognizes both forms.

BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD license was used for its namesake, the Berkeley Software Distribution (BSD), a Unix-like operating system. The original version has since been revised, and its descendants are referred to as modified BSD licenses.

<span class="mw-page-title-main">Copyleft</span> Practice of mandating free use in all derivatives of a work

Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, freedoms refers to the use of the work for any purpose, and the ability to modify, copy, share, and redistribute the work, with or without a fee. Licenses which implement copyleft can be used to maintain copyright conditions for works ranging from computer software, to documents, art, scientific discoveries and even certain patents.

<span class="mw-page-title-main">GNU General Public License</span> Series of free software licenses

The GNU General Public License is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general use and was originally written by the founder of the Free Software Foundation (FSF), Richard Stallman, for the GNU Project. The license grants the recipients of a computer program the rights of the Free Software Definition. These GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms. It is more restrictive than the Lesser General Public License and even further distinct from the more widely used permissive software licenses BSD, MIT, and Apache.

<span class="mw-page-title-main">GNU Free Documentation License</span> Copyleft license primarily for free software documentation

The GNU Free Documentation License is a copyleft license for free documentation, designed by the Free Software Foundation (FSF) for the GNU Project. It is similar to the GNU General Public License, giving readers the rights to copy, redistribute, and modify a work and requires all copies and derivatives to be available under the same license. Copies may also be sold commercially, but, if produced in larger quantities, the original document or source code must be made available to the work's recipient.


  1. Raymond, Eric S. (June 16, 1999). "Open Source Certification". Open Source Initiative . Archived from the original on December 1, 2017. Retrieved November 18, 2017.
  2. 1 2 Kelty, Christpher M. (2008). "The Cultural Significance of free Software – Two Bits" (PDF). Duke University Press. p. 99. Archived (PDF) from the original on 2016-03-04. Retrieved 2016-02-24. Prior to 1998, Free Software referred either to the Free Software Foundation (and the watchful, micromanaging eye of Stallman) or to one of thousands of different commercial, avocational, or university-research projects, Processes, licenses, and ideologies that had a variety of names: sourceware, freeware, shareware, open software, public domain software, and so on. The term Open Source, by contrast, sought to encompass them all in one movement.
  3. "Categories of free and nonfree software". Free Software Foundation . Archived from the original on December 1, 2017. Retrieved November 18, 2017.
  4. Davies, Tim (April 12, 2014). "Data, information, knowledge and power – exploring Open Knowledge's new core purpose". Tim's Blog. Archived from the original on June 29, 2017. Retrieved November 18, 2017.
  5. "Open Definition 2.1". The Open Definition . Archived from the original on January 27, 2017. Retrieved November 18, 2017.