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GNU General Public License

gnu general public license, gnu general public license version 2
The GNU General Public License GNU GPL or GPL is a widely used free software license, which guarantees end users the freedom to run, study, share and modify the software The license was originally written by Richard Stallman of the Free Software Foundation FSF for the GNU Project, and grants the recipients of a computer program the rights of the Free Software Definition The GPL is a copyleft license, which means that derivative work can only be distributed under the same license terms This is in distinction to permissive free software licenses, of which the BSD licenses and the MIT License are widely used examples GPL was the first copyleft license for general use

Historically, the GPL license family has been one of the most popular software licenses in the free and open-source software domain Prominent free software programs licensed under the GPL include the Linux kernel and the GNU Compiler Collection GCC David A Wheeler argues that the copyleft provided by the GPL was crucial to the success of Linux-based systems, giving the programmers who contributed to the kernel the assurance that their work would benefit the whole world and remain free, rather than being exploited by software companies that would not have to give anything back to the community

In 2007, the third version of the license GNU GPLv3 was released to address some perceived problems with the second version GNU GPLv2 that were discovered during its long-time usage To keep the license up to date, the GPL license includes an optional "any later version" clause, allowing users to choose between the original terms or the terms in new versions as updated by the FSF Developers can omit it when licensing their software; for instance the Linux kernel is licensed under GPLv2 without the "any later version" clause


  • 1 History
    • 11 Version 1
    • 12 Version 2
    • 13 Version 3
  • 2 Terms and conditions
    • 21 Use of licensed software
    • 22 Copyleft
    • 23 License versus contract
  • 3 Derivations
  • 4 Linking and derived works
    • 41 Libraries
      • 411 Point of view: dynamic and static linking violate GPL
      • 412 Point of view: static linking violates GPL but unclear as of dynamic linking
      • 413 Point of view: linking is irrelevant
    • 42 Communicating and bundling with non-GPL programs
  • 5 Legal status
  • 6 Compatibility and multi-licensing
    • 61 Use for text and other media
  • 7 Adoption
  • 8 Reception
    • 81 Legal barrier to app stores
    • 82 Microsoft
      • 821 "Viral" nature
    • 83 Barrier to commercialization
    • 84 Open-source criticism
    • 85 GPLv3 separates community further
  • 9 See also
  • 10 References
  • 11 External links


The GPL was written by Richard Stallman in 1989, for use with programs released as part of the GNU project The original GPL was based on a unification of similar licenses used for early versions of GNU Emacs 1985, the GNU Debugger and the GNU C Compiler These licenses contained similar provisions to the modern GPL, but were specific to each program, rendering them incompatible, despite being the same license Stallman's goal was to produce one license that could be used for any project, thus making it possible for many projects to share code

The second version of the license, version 2, was released in 1991 Over the following 15 years, members of the free software community became concerned over problems in the GPLv2 license that could let someone exploit GPL-licensed software in ways contrary to the license's intent These problems included tivoization the inclusion of GPL-licensed software in hardware that refuses to run modified versions of its software, compatibility issues similar to those of the Affero General Public License—and patent deals between Microsoft and distributors of free and open source software, which some viewed as an attempt to use patents as a weapon against the free software community

Version 3 was developed to attempt to address these concerns and was officially released on 29 June 2007

Version 1

Version 1 of the GNU GPL, released on 25 February 1989, prevented what were then the two main ways that software distributors restricted the freedoms that define free software The first problem was that distributors may publish binary files only—executable, but not readable or modifiable by humans To prevent this, GPLv1 stated that any vendor distributing binaries must also make the human-readable source code available under the same licensing terms Sections 3a and 3b of the license

The second problem was that distributors might add restrictions, either to the license, or by combining the software with other software that had other restrictions on distribution The union of two sets of restrictions would apply to the combined work, thus adding unacceptable restrictions To prevent this, GPLv1 stated that modified versions, as a whole, had to be distributed under the terms in GPLv1 Sections 2b and 4 of the license Therefore, software distributed under the terms of GPLv1 could be combined with software under more permissive terms, as this would not change the terms under which the whole could be distributed However, software distributed under GPLv1 could not be combined with software distributed under a more restrictive license, as this would conflict with the requirement that the whole be distributable under the terms of GPLv1

Version 2

According to Richard Stallman, the major change in GPLv2 was the "Liberty or Death" clause, as he calls it – Section 7 The section says that licensees may distribute a GPL-covered work only if they can satisfy all of the license's obligations, despite any other legal obligations they might have In other words, the obligations of the license may not be severed due to conflicting obligations This provision is intended to discourage any party from using a patent infringement claim or other litigation to impair users' freedom under the license

By 1990, it was becoming apparent that a less restrictive license would be strategically useful for the C library and for software libraries that essentially did the job of existing proprietary ones; when version 2 of the GPL GPLv2 was released in June 1991, therefore, a second license – the Library General Public License – was introduced at the same time and numbered with version 2 to show that both were complementary The version numbers diverged in 1999 when version 21 of the LGPL was released, which renamed it the GNU Lesser General Public License to reflect its place in the philosophy

Most commonly "GPLv2 or any later version" is stated by users of the license, to allow upgrading to GPLv3 See next section for details

Version 3

Richard Stallman at the launch of the first draft of the GNU GPLv3 MIT, Cambridge, Massachusetts, USA To his right is Columbia Law Professor Eben Moglen, chairman of the Software Freedom Law Center

In late 2005, the Free Software Foundation FSF announced work on version 3 of the GPL GPLv3 On 16 January 2006, the first "discussion draft" of GPLv3 was published, and the public consultation began The public consultation was originally planned for nine to fifteen months but finally stretched to eighteen months with four drafts being published The official GPLv3 was released by FSF on 29 June 2007 GPLv3 was written by Richard Stallman, with legal counsel from Eben Moglen and the Software Freedom Law Center

According to Stallman, the most important changes are in relation to software patents, free software license compatibility, the definition of "source code", and hardware restrictions on software modification "tivoization" Other changes relate to internationalization, how license violations are handled, and how additional permissions can be granted by the copyright holder

It also adds a provision that "strips" Digital Rights Management DRM of its legal value, so people can break anything a court might recognize as DRM on GPL software without breaking laws like the DMCA

The public consultation process was coordinated by the Free Software Foundation with assistance from Software Freedom Law Center, Free Software Foundation Europe, and other free software groups Comments were collected from the public via the gplv3fsforg web portal That portal runs purpose-written software called stet

During the public consultation process, 962 comments were submitted for the first draft By the end, a total of 2,636 comments had been submitted

The third draft was released on 28 March 2007 This draft included language intended to prevent patent-related agreements like the controversial Microsoft-Novell patent agreement and restricts the anti-tivoization clauses to a legal definition of a "User" or "consumer product" It also explicitly removed the section on "Geographical Limitations", whose probable removal had been announced at the launch of the public consultation

The fourth discussion draft, which was the last, was released on 31 May 2007 It introduced Apache License version 20 compatibility prior versions are incompatible, clarified the role of outside contractors, and made an exception to avoid the perceived problems of a Microsoft–Novell style agreement, saying in Section 11 paragraph 6 that:

You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license

This aims to make future such deals ineffective The license is also meant to cause Microsoft to extend the patent licenses it grants to Novell customers for the use of GPLv3 software to all users of that GPLv3 software; this is possible only if Microsoft is legally a "conveyor" of the GPLv3 software

Also, early drafts of GPLv3 let licensors add an Affero-like requirement that would have plugged the ASP loophole in the GPL As there were concerns expressed about the administrative costs of checking code for this additional requirement, it was decided to keep the GPL and the Affero license separated

Others, notably some high-profile developers of the Linux kernel, for instance Linus Torvalds, Greg Kroah-Hartman and Andrew Morton, commented to the mass media and made public statements about their objections to parts of discussion drafts 1 and 2 The kernel developers referred to GPLv3 draft clauses regarding DRM/Tivoization, patents and "additional restrictions" and warned a Balkanisation of the "Open Source Universe" Linus Torvalds, who decided to not adopt the GPLv3 for the Linux kernel, reiterated his criticism even years later

GPLv3 improves compatibility with several open source software licenses such as Apache License, version 20, and the GNU Affero General Public License, which GPLv2 could not be combined with But on the downside, GPLv3 software can only be combined and share code with GPLv2 software if the used GPLv2 license has the optional "or later" clause and the software is upgraded to GPLv3 While the "GPLv2 or any later version" clause is considered by FSF as the most common form of licensing GPLv2 software, for example Toybox developer Rob Landley described it as a lifeboat clause Software projects licensed with the optional "or later" clause include the GNU Project, while a prominent example without the clause is the Linux kernel

The final version of the license text was published on 29 June 2007

Terms and conditions

The terms and conditions of the GPL must be made available to anybody receiving a copy of the work that has a GPL applied to it "the licensee" Any licensee who adheres to the terms and conditions is given permission to modify the work, as well as to copy and redistribute the work or any derivative version The licensee is allowed to charge a fee for this service, or do this free of charge This latter point distinguishes the GPL from software licenses that prohibit commercial redistribution The FSF argues that free software should not place restrictions on commercial use, and the GPL explicitly states that GPL works may be sold at any price

The GPL additionally states that a distributor may not impose "further restrictions on the rights granted by the GPL" This forbids activities such as distributing of the software under a non-disclosure agreement or contract

The fourth section for version 2 of the license and the seventh section of version 3 require that programs distributed as pre-compiled binaries be accompanied by a copy of the source code, a written offer to distribute the source code via the same mechanism as the pre-compiled binary, or the written offer to obtain the source code that the user got when they received the pre-compiled binary under the GPL The second section of version 2 and the fifth section of version 3 also require giving "all recipients a copy of this License along with the Program" Version 3 of the license allows making the source code available in additional ways in fulfillment of the seventh section These include downloading source code from an adjacent network server or by peer-to-peer transmission, provided that is how the compiled code was available and there are "clear directions" on where to find the source code

The FSF does not hold the copyright for a work released under the GPL, unless an author explicitly assigns copyrights to the FSF which seldom happens except for programs that are part of the GNU project Only the individual copyright holders have the authority to sue when a license violation takes place

Printed GPL statements for consumer entertainment devices which incorporate GPL components

Use of licensed software

Software under the GPL may be run for all purposes, including commercial purposes and even as a tool for creating proprietary software, for example when using GPL-licensed compilers Users or companies who distribute GPL-licensed works eg software, may charge a fee for copies or give them free of charge This distinguishes the GPL from shareware software licenses that allow copying for personal use but prohibit commercial distribution, or proprietary licenses where copying is prohibited by copyright law The FSF argues that freedom-respecting free software should also not restrict commercial use and distribution including redistribution: the GPL explicitly states that GPL works may be sold at any price

In purely private or internal use—with no sales and no distribution—the software code may be modified and parts reused without requiring the source code to be released For sales or distribution, the entire source code need to be made available to end users, including any code changes and additions—in that case, copyleft is applied to ensure that end users retain the freedoms defined above

However, software running as an application program under a GPL-licensed operating system such as Linux is not required to be licensed under GPL or to be distributed with source-code availability—the licensing depends only on the used libraries and software components and not on the underlying platform For example, if a program consists only of own original custom software, or is combined with source code from other software components, then the own custom software components need not be licensed under GPL and need not make their code available; even if the underlying operating system used is licensed under the GPL, applications running on it are not considered derivative works Only if GPLed parts are used in a program and the program is distributed, then all other source code of the program needs to be made available under the same license terms The GNU Lesser General Public license LGPL was created to have a weaker copyleft than the GPL, in that it does not require own custom-developed source code distinct from the LGPLed parts to be made available under the same license terms


Main article: Copyleft

The distribution rights granted by the GPL for modified versions of the work are not unconditional When someone distributes a GPL'd work plus his/her own modifications, the requirements for distributing the whole work cannot be any greater than the requirements that are in the GPL

This requirement is known as copyleft It earns its legal power from the use of copyright on software programs Because a GPL work is copyrighted, a licensee has no right to redistribute it, not even in modified form barring fair use, except under the terms of the license One is only required to adhere to the terms of the GPL if one wishes to exercise rights normally restricted by copyright law, such as redistribution Conversely, if one distributes copies of the work without abiding by the terms of the GPL for instance, by keeping the source code secret, he or she can be sued by the original author under copyright law

Copyleft thus uses copyright law to accomplish the opposite of its usual purpose: instead of imposing restrictions, it grants rights to other people, in a way that ensures the rights cannot subsequently be taken away It also ensures that unlimited redistribution rights are not granted, should any legal flaw be found in the copyleft statement

Many distributors of GPL'ed programs bundle the source code with the executables An alternative method of satisfying the copyleft is to provide a written offer to provide the source code on a physical medium such as a CD upon request In practice, many GPL'ed programs are distributed over the Internet, and the source code is made available over FTP or HTTP For Internet distribution, this complies with the license

Copyleft applies only when a person seeks to redistribute the program Developers may make private modified versions with no obligation to divulge the modifications, as long as they don't distribute the modified software to anyone else Note that copyleft applies only to the software, and not to its output unless that output is itself a derivative work of the program For example, a public web portal running a modified derivative of a GPL'ed content management system is not required to distribute its changes to the underlying software, because its output is not a derivative

There has been debate on whether it is a violation of the GPL to release the source code in obfuscated form, such as in cases in which the author is less willing to make the source code available The consensus was that while unethical, it was not considered a violation The issue was clarified when the license was altered with v2 to require that the "preferred" version of the source code be made available

License versus contract

The GPL was designed as a license, rather than a contract In some Common Law jurisdictions, the legal distinction between a license and a contract is an important one: contracts are enforceable by contract law, whereas licenses are enforced under copyright law However, this distinction is not useful in the many jurisdictions where there are no differences between contracts and licenses, such as Civil Law systems

Those who do not accept the GPL's terms and conditions do not have permission, under copyright law, to copy or distribute GPL licensed software or derivative works However, if they do not redistribute the GPL'd program, they may still use the software within their organization however they like, and works including programs constructed by the use of the program are not required to be covered by this license

Allison Randal argued that the GPLv3 as a license is unnecessarily confusing for lay readers, and could be simplified while retaining the same conditions and legal force


The text of the GPL is itself copyrighted, and the copyright is held by the Free Software Foundation

The FSF permits people to create new licenses based on the GPL, as long as the derived licenses do not use the GPL preamble without permission This is discouraged, however, since such a license might be incompatible with the GPL and causes a perceived license proliferation

Other licenses created by the GNU project include the GNU Lesser General Public License, the GNU Free Documentation License and Affero General Public License

The text of the GPL is not itself under the GPL The license's copyright disallows modification of the license Copying and distributing the license is allowed since the GPL requires recipients to get "a copy of this License along with the Program" According to the GPL FAQ, anyone can make a new license using a modified version of the GPL as long as he or she uses a different name for the license, does not mention "GNU", and removes the preamble, though the preamble can be used in a modified license if permission to use it is obtained from the Free Software Foundation FSF

Linking and derived works


According to the FSF, "The GPL does not require you to release your modified version, or any part of it You are free to make modifications and use them privately, without ever releasing them" However, if one releases a GPL-licensed entity to the public, there is an issue regarding linking: namely, whether a proprietary program that uses a GPL library is in violation of the GPL

This key dispute is whether non-GPL software can legally statically link or dynamically link to GPL libraries Different opinions exist on this issue The GPL is clear in requiring that all derivative works of code under the GPL must themselves be under the GPL Ambiguity arises with regards to using GPL libraries, and bundling GPL software into a larger package perhaps mixed into a binary via static linking This is ultimately a question not of the GPL per se, but of how copyright law defines derivative works The following points of view exist:

Point of view: dynamic and static linking violate GPL

The Free Software Foundation which holds the copyright of several notable GPL-licensed software products and of the license text itself asserts that an executable which uses a dynamically linked library is indeed a derivative work This does not however apply to separate programs communicating with one another

The Free Software Foundation also created the LGPL, which is nearly identical to the GPL, but with additional permissions to allow linking for the purposes of "using the library"

Richard Stallman and the FSF specifically encourage library-writers to license under the GPL so that proprietary programs cannot use the libraries, in an effort to protect the free-software world by giving it more tools than the proprietary world

Point of view: static linking violates GPL but unclear as of dynamic linking

Some people believe that while static linking produces derivative works, it is not clear whether an executable that dynamically links to a GPL code should be considered a derivative work see Weak Copyleft Linux author Linus Torvalds agrees that dynamic linking can create derived works but disagrees over the circumstances

A Novell lawyer has written that dynamic linking not being derivative "makes sense" but is not "clear-cut", and that evidence for good-intentioned dynamic linking can be seen by the existence of proprietary Linux kernel drivers

In Galoob v Nintendo the United States Ninth Circuit Court of Appeals defined a derivative work as having "'form' or permanence" and noted that "the infringing work must incorporate a portion of the copyrighted work in some form", but there have been no clear court decisions to resolve this particular conflict

Point of view: linking is irrelevant

According to an article in the Linux Journal, Lawrence Rosen a one-time Open Source Initiative general counsel argues that the method of linking is mostly irrelevant to the question about whether a piece of software is a derivative work; more important is the question about whether the software was intended to interface with client software and/or libraries He states, "The primary indication of whether a new program is a derivative work is whether the source code of the original program was used , modified, translated or otherwise changed in any way to create the new program If not, then I would argue that it is not a derivative work," and lists numerous other points regarding intent, bundling, and linkage mechanism He further argues on his firm's website that such "market-based" factors are more important than the linking technique

There is also the specific issue of whether a plugin or module such as the NVidia or ATI graphics card kernel modules must also be GPL, if it could reasonably be considered its own work This point of view suggests that reasonably separate plugins, or plugins for software designed to use plugins, could be licensed under an arbitrary license if the work is GPLv2 Of particular interest is the GPLv2 paragraph:

You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:

b You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License These requirements apply to the modified work as a whole If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it

The GPLv3 has a different clause:

You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of Section 4, provided that you also meet all of these conditions:

c You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy This License will therefore apply, along with any applicable Section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an "aggregate" if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation's users beyond what the individual works permit Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate

As a case study, some supposedly proprietary plugins and themes/skins for GPLv2 CMS software such as Drupal and WordPress have come under fire, with both sides of the argument taken

The FSF differentiates on how the plugin is being invoked If the plugin is invoked through dynamic linkage and it performs function calls to the GPL program then it is most likely a derivative work

Communicating and bundling with non-GPL programs

The mere act of communicating with other programs does not, by itself, require all software to be GPL; nor does distributing GPL software with non-GPL software However, minor conditions must be followed that ensures the rights of GPL software is not restricted The following is a quote from the gnuorg GPL FAQ, which describes to what extent software is allowed to communicate with and be-bundled-with GPL programs:

What is the difference between an "aggregate" and other kinds of "modified versions"

An "aggregate" consists of a number of separate programs, distributed together on the same CD-ROM or other media The GPL permits you to create and distribute an aggregate, even when the licenses of the other software are non-free or GPL-incompatible The only condition is that you cannot release the aggregate under a license that prohibits users from exercising rights that each program's individual license would grant them

Where's the line between two separate programs, and one program with two parts This is a legal question, which ultimately judges will decide We believe that a proper criterion depends both on the mechanism of communication exec, pipes, rpc, function calls within a shared address space, etc and the semantics of the communication what kinds of information are interchanged

If the modules are included in the same executable file, they are definitely combined in one program If modules are designed to run linked together in a shared address space, that almost surely means combining them into one program

By contrast, pipes, sockets and command-line arguments are communication mechanisms normally used between two separate programs So when they are used for communication, the modules normally are separate programs But if the semantics of the communication are intimate enough, exchanging complex internal data structures, that too could be a basis to consider the two parts as combined into a larger program

The FSF thus draws the line between "library" and "other program" via 1 "complexity" and "intimacy" of information exchange, and 2 mechanism rather than semantics, but resigns that the question is not clear-cut and that in complex situations, case law will decide

Legal status

The first known violation of the GPL was in 1989, when NeXT extended the GCC compiler to support Objective-C, but did not publicly release the changes After an inquiry they created a public patch There was no lawsuit filed for this violation

In 2002, MySQL AB sued Progress NuSphere for copyright and trademark infringement in United States district court NuSphere had allegedly violated MySQL's copyright by linking MySQL's GPL'ed code with NuSphere Gemini table without being in compliance with the license After a preliminary hearing before Judge Patti Saris on 27 February 2002, the parties entered settlement talks and eventually settled After the hearing, FSF commented that "Judge Saris made clear that she sees the GNU GPL to be an enforceable and binding license"

In August 2003, the SCO Group stated that they believed the GPL to have no legal validity, and that they intended to pursue lawsuits over sections of code supposedly copied from SCO Unix into the Linux kernel This was a problematic stand for them, as they had distributed Linux and other GPL'ed code in their Caldera OpenLinux distribution, and there is little evidence that they had any legal right to do so except under the terms of the GPL For more information, see SCO-Linux controversies and SCO v IBM

In April 2004, the netfilter/iptables project was granted a preliminary injunction against Sitecom Germany by Munich District Court after Sitecom refused to desist from distributing Netfilter's GPL'ed software in violation of the terms of the GPL Harald Welte, of Netfilter, was represented by ifrOSS co-founder Till Jaeger On July 2004, the German court confirmed this injunction as a final ruling against Sitecom The court's justification was that:

Defendant has infringed on the copyright of plaintiff by offering the software 'netfilter/iptables' for download and by advertising its distribution, without adhering to the license conditions of the GPL Said actions would only be permissible if defendant had a license grant This is independent of the questions whether the licensing conditions of the GPL have been effectively agreed upon between plaintiff and defendant or not If the GPL were not agreed upon by the parties, defendant would notwithstanding lack the necessary rights to copy, distribute, and make the software 'netfilter/iptables' publicly available

This exactly mirrored the predictions given previously by the FSF's Eben Moglen This ruling was important because it was the first time that a court had confirmed that violating terms of the GPL could be a copyright violation and established jurisprudence as to the enforceability of the GPL version 2 under German law

In May 2005, Daniel Wallace filed suit against the Free Software Foundation in the Southern District of Indiana, contending that the GPL is an illegal attempt to fix prices at zero The suit was dismissed in March 2006, on the grounds that Wallace had failed to state a valid anti-trust claim; the court noted that "the GPL encourages, rather than discourages, free competition and the distribution of computer operating systems, the benefits of which directly pass to consumers" Wallace was denied the possibility of further amending his complaint, and was ordered to pay the FSF's legal expenses

On 8 September 2005, the Seoul Central District Court ruled that the GPL was not material to a case dealing with trade secrets derived from GPL-licensed work Defendants argued that since it is impossible to maintain trade secrets while being compliant with GPL and distributing the work, they are not in breach of trade secrets This argument was considered without ground

On 6 September 2006, the gpl-violationsorg project prevailed in court litigation against D-Link Germany GmbH regarding D-Link's copyright-infringing use of parts of the Linux Kernel in storage devices they distributed The judgment stated that the GPL is valid, legally binding, and stands in German court

In late 2007, the BusyBox developers and the Software Freedom Law Center embarked upon a program to gain GPL compliance from distributors of BusyBox in embedded systems, suing those who would not comply These were claimed to be the first US uses of courts for enforcement of GPL obligations See BusyBox GPL lawsuits

On 11 December 2008, the Free Software Foundation sued Cisco Systems, Inc for copyright violations by its Linksys division, of the FSF's GPL-licensed coreutils, readline, Parted, Wget, GNU Compiler Collection, binutils, and GNU Debugger software packages, which Linksys distributes in the Linux firmware of its WRT54G wireless routers, as well as numerous other devices including DSL and Cable modems, Network Attached Storage devices, Voice-Over-IP gateways, Virtual Private Network devices and a home theater/media player device

After six years of repeated complaints to Cisco by the FSF, claims by Cisco that they would correct, or were correcting, their compliance problems not providing complete copies of all source code and their modifications, of repeated new violations being discovered and reported with more products, and lack of action by Linksys a process described on the FSF blog as a "five-years-running game of Whack-a-Mole" the FSF took them to court

Cisco settled the case six months later by agreeing "to appoint a Free Software Director for Linksys" to ensure compliance, "to notify previous recipients of Linksys products containing FSF programs of their rights under the GPL," to make source code of FSF programs freely available on its website, and to make a monetary contribution to the FSF

Compatibility and multi-licensing

Quick Guide of license compatibility with GPLv3 according to the FSF Dashed line indicates that the GPLv2 is only compatible with the GPLv3 if with the clause "or any later"

Code licensed under several other licenses can be combined with a program under the GPL without conflict, as long as the combination of restrictions on the work as a whole does not put any additional restrictions beyond what GPL allows In addition to the regular terms of the GPL, there are additional restrictions and permissions one can apply:

  1. If a user wants to combine code licensed under different versions of GPL, then this is only allowed if the code with the older GPL version includes an "any later version" statement For instance, the GPLv3 licensed GNU LibreDWG library can't be used anymore by LibreCAD and FreeCAD who have GPLv2 only dependencies
  2. Code licensed under LGPL is permitted to be linked with any other code no matter what license that code has, though the LGPL does add additional requirements for the combined work LGPLv3 and GPLv2-only can thus commonly not be linked, as the combined Code work would add additional LGPLv3 requirements on top of the GPLv2-only licensed software Code licensed under LGPLv2x without the "any later version" statement can be relicensed if the whole combined work is licensed to GPLv2 or GPLv3

FSF maintains a list of GPL-compatible free software licenses with many of the most common free software licenses, such as the original MIT/X license, the BSD license in its current 3-clause form and the Artistic License 20

David A Wheeler has advocated that free/open source software developers use only GPL-compatible licenses, because doing otherwise makes it difficult for others to participate and contribute code As a specific example of license incompatibility, Sun Microsystems' ZFS cannot be included in the GPL-licensed Linux kernel, because it is licensed under the GPL-incompatible CDDL Furthermore, ZFS is protected by patents, so distributing an independently developed GPL-ed implementation would still require Oracle's permission

A number of businesses use multi-licensing to distribute a GPL version and sell a proprietary license to companies wishing to combine the package with proprietary code, using dynamic linking or not Examples of such companies include MySQL AB, Digia PLC Qt framework, before 2011 from Nokia, Red Hat Cygwin and Riverbank Computing PyQt Other companies, like the Mozilla Foundation products include Mozilla Application Suite, Mozilla Thunderbird and Mozilla Firefox, used multi-licensing to distribute versions under the GPL and some other open-source licenses

Use for text and other media

It is possible to use the GPL for text documents instead of computer programs, or more generally for all kinds of media, if it is clear what constitutes the source code defined as "the preferred form of the work for making changes in it" For manuals and textbooks, though, the FSF recommends the GNU Free Documentation License GFDL instead, which it created for this purpose Nevertheless, the Debian developers recommended in a resolution adopted in 2006 to license documentation for their project under the GPL, because of the incompatibility of the GFDL with the GPL text licensed under the GFDL cannot be incorporated into GPL software Also, the FLOSS Manuals foundation, an organization devoted to creating manuals for free software, decided to eschew the GFDL in favor of the GPL for its texts in 2007

If the GPL is used for fonts, any documents or images made with such fonts might also have to be distributed under the terms of the GPL This is not the case in countries like the US and Canada where copyright law is inapplicable to the appearance of fonts, though program code inside a font file may still be covered—which can complicate font embedding since the document could be considered 'linked' to the font FSF provides an exception for cases where this is not desired


Historically, the GPL license family has been one of the most popular software licenses in the FOSS domain

A 1997 survey of MetaLab, then the largest free software archive, showed that the GPL accounted for about half of the software licensed therein Similarly, a 2000 survey of Red Hat Linux 71 found that 53% of the source code was licensed under the GPL As of 2003, about 68% of all projects and 821% of the OSI certified licensed projects listed on SourceForgenet were from the GPL license family As of August 2008, the GPL family accounted for 709% of the 44,927 free software projects listed on Freecode

After the release of the GPLv3 in June 2007, adoption of this new GPL version was much discussed and some projects decided against upgrading For instance the linux kernel, MySQL, BusyBox, AdvFS, and VLC media player decided against adopting the GPLv3 On the other hand, in 2009, two years after the release of the GPLv3, Google open-source programs office manager Chris DiBona reported that the number of open-source projects licensed software that had moved to GPLv3 from GPLv2 was 50%, counting the projects hosted at Google Code

In 2011, four years after the release of the GPLv3, 65% of all open-source license projects are GPLv3 while 425% are GPLv2 according to Black Duck Software data Following in 2011 451 Group analyst Matthew Aslett argued in a blog post that copyleft licenses went into decline and permissive licenses increased, based on statistics from Black Duck Software Similarly, in February 2012 Jon Buys reported that among the top 50 projects on GitHub five projects were under a GPL license, including dual licensed and AGPL projects

GPL usage statistic from 2009 to 2013 was extracted from Freecode data by Walter van Holst while analyzing license proliferation

Usage of GPL family licenses in % on Freecode
2009 2010 2011 2012 2013 2014-06-18
72% 63% 61% 59% 58% approx 54%

In August 2013, according to Black Duck Software, the website's data show that the GPL license family is used by 54% of open-source projects, with a breakdown of the individual licenses shown in the following table However, a later study in 2013 showed that software licensed under the GPL license family has increased, and that even the data from Black Duck Software have shown a total increase of software projects licensed under GPL The study used public information gathered from repositories of the Debian Project, and the study criticized Black Duck Software for not publishing their methodology used in collecting statistics Daniel German, Professor in the Department of Computer Science at the University of Victoria in Canada, presented a talk in 2013 about the methodological challenges in determining which are the most widely used free software licenses, and showed how he could not replicate the result from Black Duck Software

In 2015 according to BlackDuck the GPLv2 lost its first position on the MIT license and is now second, the GPLv3 dropped to fourth place while the Apache license kept its third position

Usage of GPL family licenses in the FOSS domain in % according to Black Duck Software
License 2008-05-08 2009-03-11 2011-11-22 2013-08-12 2015-11-19 2016-06-06
GPLv2 5869% 522% 425% 33% 23% 21%
GPLv3 164% 415% 65% 12% 9% 9%
LGPL 21 1139% 984%   6% 5% 4%
LGPL 30   <064% 037%   3% 2% 2%
GPL family together 7172% + <064% 6656%   54% 39% 36%

A March 2015 analysis of the GitHub repositories revealed for the GPL license family an usage percentage of approx 25% among licensed projects In June 2016 an analysis of Fedora Project's packages revealed the GNU GPL version 2 or later as the most popular license, and the GNU GPL family as the most popular license family followed by the MIT, BSD, and GNU LGPL families


Legal barrier to app stores

The GPL License is incompatible with many application digital distribution systems, like the Mac App Store, and certain other software distribution platforms on smartphones as well as PCs The problem lies in the right "To make a copy for your neighbour", as this right is violated by the integrated DRM-Systems made to prevent copying of paid software Even if the application is free-as-in-beer in the App Store in question, it might result in a violation of that app store's terms

Note that there is a distinction between an app store, which sells DRM-restricted software under proprietary licenses, and the more general concept of digital distribution via some form of online software repository Various UNIX-like distributions provide app repositories, including Fedora, RHEL, CentOS, Ubuntu, Debian, FreeBSD, OpenBSD and so on These specific app repos all contain GPL-licensed software apps, in some cases even when the core project does not permit GPL-licensed code in the base system for instance OpenBSD In other cases, such as the Ubuntu App Store, proprietary commercial software applications and GPL-licensed applications are both available via the same system; the reason that the Mac App Store and similar projects is incompatible with GPL-licensed apps is not inherent in the concept of an app store, but is rather specifically due to Apple's terms-of-use requirement that all apps in the store utilize Apple DRM-restrictions Ubuntu's app store does not demand any such requirement: "These terms do not limit or restrict your rights under any applicable open source software licenses"


In 2001, Microsoft CEO Steve Ballmer referred to Linux as "a cancer that attaches itself in an intellectual property sense to everything it touches" In response to Microsoft's attacks on the GPL, several prominent Free Software developers and advocates released a joint statement supporting the license Microsoft has released Microsoft Windows Services for UNIX, which contains GPL-licensed code In July 2009, Microsoft itself released a body of around 20,000 lines of Linux driver code under the GPL The Hyper-V code that is part of the submitted code used open-source components licensed under the GPL and was originally statically linked to proprietary binary parts, the latter being inadmissible in GPL-licensed software

"Viral" nature

The description of the GPL as "viral", when called 'General Public Virus' or 'GNU Public Virus' GPV, dates back to a year after the GPLv1 was released

In 2001 the term received broader public attention when Craig Mundie, Microsoft Senior Vice President, described the GPL as being "viral" Mundie argues that the GPL has a "viral" effect in that it only allows the conveyance of whole programs, which means programs that link to GPL libraries must themselves be under a GPL-compatible license, else they cannot be combined and distributed

In 2006 Richard Stallman responded in an interview that Mundie's metaphor of a "virus" is wrong as software under the GPL does not "attack" or "infect" other software Stallman believes that comparing the GPL to a virus is an extremely unfriendly thing to say, and that a better metaphor for software under the GPL would be a spider plant: If one takes a piece of it and puts it somewhere else, it grows there too

On the other hand, the concept of a viral nature of the GPL was taken up by others later too For instance in 2008 the California Western School of Law characterized the GPL as: "The GPL license is ‘viral,’ meaning any derivative work you create containing even the smallest portion of the previously GPL licensed software must also be licensed under the GPL license"

Barrier to commercialization

Main article: Business models for open-source software

The FreeBSD project has stated that "a less publicized and unintended use of the GPL is that it is very favorable to large companies that want to undercut software companies In other words, the GPL is well suited for use as a marketing weapon, potentially reducing overall economic benefit and contributing to monopolistic behavior" and that the GPL can "present a real problem for those wishing to commercialize and profit from software"

Richard Stallman wrote about the practice of selling license exceptions to free software licenses as an example of ethically acceptable commercialization practice Selling exceptions here means that the copyright holder of a given software releases it along with the corresponding source code to the public under a free software license, "then lets customers pay for permission to use the same code under different terms, for instance allowing its inclusion in proprietary applications" Stallman considered selling exceptions "acceptable since the 1990s, and on occasion I've suggested it to companies Sometimes this approach has made it possible for important programs to become free software" Despite that the FSF doesn't practice selling exceptions, a comparison with the X11 license which is a non-copyleft free software license is proposed for suggesting that this commercialization technique should be regarded as ethically acceptable Releasing a given program under a noncopyleft free software license would permit embedding the code in proprietary software Stallman comments that "either we have to conclude that it's wrong to release anything under the X11 license—a conclusion I find unacceptably extreme—or reject this implication Using a noncopyleft license is weak, and usually an inferior choice, but it's not wrong In other words, selling exceptions permits some embedding in proprietary software, and the X11 license permits even more embedding If this doesn't make the X11 license unacceptable, it doesn't make selling exceptions unacceptable"

Open-source criticism

In 2000 developer and author Nikolai Bezroukov published an analysis and comprehensive critique of GPL's foundations and Stallman's software development model, called "Labyrinth of Software Freedom"

In 2005, open source software advocate Eric S Raymond questioned the relevance of GPL at that point in time for the FOSS ecosystem, stating: "We don't need the GPL anymore It's based on the belief that open source software is weak and needs to be protected Open source would be succeeding faster if the GPL didn't make lots of people nervous about adopting it" Richard Stallman replied that: "GPL ensure that every user of a program gets the essential freedoms—to run it, to study and change the source code, to redistribute copies, and to publish modified versions addresses the issue in terms of different goals and values—those of "open source," which do not include defending software users' freedom to share and change software"

In 2007 Allison Randal, who took part in the GPL draft committee, criticized the GPLv3 for being incompatible with the GPLv2 and for missing clarity in the formulation Similarly, Whurley prophesised in 2007 the downfall of the GPL due to the lack of focus for the developers with GPLv3 which would drive them towards permissive licenses

In 2009 David Chisnall described in an InformIT article, "The Failure of the GPL", the problems with the GPL, among them incompatibility and complexity of the license text

In 2014 dtrace developer and Joyent CTO Bryan Cantrill called the copyleft GPL a "Corporate Open Source Anti-pattern" by being "anti-collaborative" and recommended instead permissive software licenses

GPLv3 separates community further

Already in September 2006, in the draft process of the GPLv3, several high-profile developers of the Linux kernel, for instance Linus Torvalds, Greg Kroah-Hartman and Andrew Morton, warned on a splitting of the FOSS community: "the release of GPLv3 portends the Balkanisation of the entire Open Source Universe upon which we rely" Similarly Benjamin Mako Hill argued in 2006 on the GPLv3 draft, noting that a united, collaborating community is more important than a single license

Following the GPLv3 release in 2007, some journalists and Toybox developer Rob Landley criticized that with the introduction of the GPLv3 the split between the open source and free software community became wider than ever As the significantly extended GPLv3 is essentially incompatible with the GPLv2, compatibility between both is only given under the optional "or later" clause of the GPL, which was not taken for instance by the Linux kernel Bruce Byfield noted that before the release of the GPLv3, the GPLv2 was a unifying element between the open-source and the free software community

For the LGPLv3, GNU TLS maintainer Nikos Mavrogiannopoulos similarly argued, "If we assume that its primary goal is to be used by free software, then it blatantly fails that", after he re-licensed GNU TLS from LGPLv3 back to LGPLv21 due to license compatibility issues

Lawrence Rosen, attorney and computer specialist, praised in 2007 how the community using the Apache license were now able to work together with the GPL community in a compatible manner, as the problems of GPLv2 compatibility with Apache licensed software were resolved with the GPLv3 He said, "I predict that one of the biggest success stories of GPLv3 will be the realization that the entire universe of free and open source software can thus be combined into comprehensive open source solutions for customers worldwide"

In July 2013 Flask developer Armin Ronacher draw a less optimistic resume on the GPL compatibility in the FOSS ecosystem when he concluded:"When the GPL is involved the complexities of licensing becomes a non fun version of a riddle", also noting that the ASL 20 GPLv2 conflict still has impact on the ecosystem

See also

  • Free software portal
  • Anti-copyright
  • Dual-licensing
  • European Union Public Licence EUPL
  • GPL font exception
  • List of software licenses
  • Permissive and copyleft licenses


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  122. ^ Mark 2008-05-08 "The Curse of Open Source License Proliferation" socializedsoftwarecom Retrieved 2015-11-30 GNU General Public License GPL 20 5869% GNU Lesser General Public License LGPL 21 1139% Artistic License Perl 746% BSD License 650% Apache License 20 292% MIT License 258% GNU General Public Liense GPL 30 164% Mozilla Public License MPL 11 137% Common Public License 083% zlib/lippng License 064% 
  123. ^ Top 20 Most Commonly Used Open Source Licenses Shaun Connolly, March 11, 2009
  124. ^ "Top 20 licenses" Black Duck Software 6 June 2016 Retrieved 6 June 2016 1 MIT License 26% 2 GNU General Public License GPL 20 21% 3 Apache License 20 16% GNU General Public License GPL 30 9% 5 BSD License 20 3-clause, New or Revised License 6% 6 GNU Lesser General Public License LGPL 21 4% 7 Artistic License Perl 4% 8 GNU Lesser General Public License LGPL 30 2% 9 ISC License 2% 10 Microsoft Public License 2% 11 Eclipse Public License EPL 2% 12 Code Project Open License 102 1% 13 Mozilla Public License MPL 11 < 1% 14 Simplified BSD License BSD < 1% 15 Common Development and Distribution License CDDL < 1% 16 GNU Affero General Public License v3 or later < 1% 17 Microsoft Reciprocal License < 1% 18 Sun GPL With Classpath Exception v20 < 1% 19 DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE < 1% 20 CDDL-11 
  125. ^ Balter, Ben 2015-03-09 "Open source license usage on GitHubcom" githubcom Retrieved 2015-11-21 1 MIT 4469%, 2 Other 1568%, 3 GPLv2 1296%, 4 Apache 1119%, 5 GPLv3 888%, 6 BSD 3-clause 453%, 7 Unlicense 187%, 8 BSD 2-clause 170%, 9 LGPLv3 130%, 10 AGPLv3 105% 
  126. ^ Anwesha Das 22 June 2016 "Software Licenses in Fedora Ecosystem" anweshadasin Retrieved 2016-11-01 From the above chart it is clear that the GPL family is the highest used I had miscalculated it as MIT beforeThe other major licenses are MIT, BSD, the LGPL family, Artistic for Perl packages, LPPL fo texlive packages, ASL 
  127. ^ a b "The GPL, the App Store and You" on tuawcom 2011
  128. ^ "Copyright Policy", OpenBSD
  129. ^ "Ubuntu One : Terms and Conditions" Oneubuntucom 29 August 2013 Retrieved 25 September 2013 
  130. ^ Newbart, Dave 1 June 2001 "Microsoft CEO takes launch break with the Sun-Times" Chicago Sun-Times Archived from the original on 15 June 2001 Internet archive link
  131. ^ text of GPL v1 with reference to source code download site at microsoftcom
  132. ^  Free Software Leaders Stand Together Wikisource 
  133. ^ Clarke, Gavin 20 July 2009 "Microsoft embraces Linux cancer to sell Windows servers" The Register 
  134. ^ Clarke, Gavin 23 July 2009 "Microsoft opened Linux-driver code after 'violating' GPL" The Register 
  135. ^ Vixie, Paul 6 March 2006 "Re: Section 52 IPR encumberance in TAK rollover requirement draft" IETF Namedroppers mailing list Archived from the original on 27 September 2007 Retrieved 29 April 2007 
  136. ^ "General Public Virus" Jargon File 221 15 December 1990 Retrieved 29 April 2007 
  137. ^ Hackvän, Stig September 1999 "Reverse-engineering the GNU Public Virus — Is copyleft too much of a good thing" Linux Journal Retrieved 29 April 2007 
  138. ^ Stewart, Bill 8 October 1998 "Re: propose: `cypherpunks license' Re: Wanted: Twofish source code" Cypherpunks mailing list Retrieved 29 April 2007 
  139. ^ Buck, Joe 10 October 2000 "Re: Using of parse tree externally" GCC mailing list Retrieved 29 April 2007 
  140. ^ Griffis, L Adrian 15 July 2000 "The GNU Public Virus" Retrieved 29 April 2007 
  141. ^ "Speech Transcript – Craig Mundie, The New York University Stern School of Business", Prepared Text of Remarks by Craig Mundie, Microsoft Senior Vice President, The Commercial Software Model The New York University Stern School of Business 3 May 2001
  142. ^ Poynder, Richard 21 March 2006 "The Basement Interviews: Freeing the Code" Retrieved 5 February 2010 
  143. ^ Chopra, Samir; Dexter, Scott 14 August 2007 Decoding liberation: the promise of free and open source software Routledge p 56 ISBN 0-415-97893-9 
  144. ^ Williams, Sam March 2002 Free as in Freedom: Richard Stallman's Crusade for Free Software O'Reilly Media ISBN 0-596-00287-4 
  145. ^ Nikolai Bezroukov 2001 "Comparative merits of GPL, BSD and Artistic licences Critique of Viral Nature of GPL v2 - or In Defense of Dual Licensing Idea" Archived from the original on 2001-12-22 Viral property stimulates proliferation of licenses and contributes to the "GPL-enforced nightmare" -- a situation when many other licenses are logically incompatible with the GPL and make life unnecessary difficult for developers working in the Linux environment KDE is a good example here, Python is a less known example 
  146. ^ Geere, Duncan 2011-12-16 "Some rights reserved: the alternatives to copyright Wired UK" Wiredcouk Retrieved 2015-05-30 
  147. ^ "Glossary" A2Knetworkorg Retrieved 2015-05-30 
  148. ^ "Inoculating Your Purchase – Contractual Protection from Viral Licenses in M&A Transactions" PDF Friedfrankcom Retrieved 2015-05-30 
  149. ^ Archived 16 March 2015 at the Wayback Machine
  150. ^ New Media Rights 2008-09-12 "Open Source Licensing Guide" California Western School of Law Retrieved 2015-11-28 The GPL license is ‘viral,’ meaning any derivative work you create containing even the smallest portion of the previously GPL licensed software must also be licensed under the GPL license 
  151. ^ Montague, Bruce 2013-11-13 "GPL Advantages and Disadvantages" FreeBSD Retrieved 2015-11-28 
  152. ^ Richard Stallman 2010 On Selling Exceptions to the GNU GPL Free Software Foundation
  153. ^ Bezroukov, Labyrinth of Software Freedom - "BSD vs GPL and social aspects of free licensing debate" on softpanoramaorg by Nikolai Bezroukov Accessed 23 September 2010
  154. ^ The Scope of Open Source Licensing - Harvard University by Josh Lerner and Jean Tirole 2002
  155. ^ Biancuzzi, Federico 2005-06-30 "ESR: "We Don't Need the GPL Anymore"" onlampcom Retrieved 2015-02-10 "We don't need the GPL anymore It's based on the belief that open source software is weak and needs to be protected Open source would be succeeding faster if the GPL didn't make lots of people nervous about adopting it" 
  156. ^ "RMS: The GNU GPL Is Here to Stay" onlampcom 2005-09-22 Retrieved 2015-02-12 "ESR addresses the issue in terms of different goals and values—those of "open source," which do not include defending software users' freedom to share and change software Perhaps he thinks the GNU GPL is not needed to achieve those goals" 
  157. ^ Randal, Allison April 13, 2007 "GPLv3, Linux and GPLv2 Compatibility" radaroreillycom O'Reilly Media Retrieved 2016-01-19 You might think the FSF would have to be insane to unleash this licensing hell If the license were purely a cleaned up version of the GPLv2, there would be no incompatibility, the FSF would have no agenda involved in getting projects to update to the new license, and at the same time there would be no reason for projects to object to updating Smooth sailing 
  158. ^ Randal, Allison May 14, 2007 "GPLv3, Clarity and Simplicity" radaroreillycom O'Reilly Media Retrieved 2016-01-19 Looking at the near-finished draft, I have to say it’s unlikely that they ever considered simplicity a priority, if they considered it at all The language choices of an open source license can support that freedom, can empower the users and the developers The GPLv3 doesn’t 
  159. ^ Whurley 2007-06-06 "The Death Of A Software License" Archived from the original on 2008-10-11 Retrieved 2016-06-24 Version 3 is going to distance Richard Stallman and the Free Software Foundation from the developers that make the organization so influential to begin 
  160. ^ Chisnall, David 2009-08-31 "The Failure of the GPL" informitcom Retrieved 2016-01-24 
  161. ^ Cantrill, Bryan 2014-09-17 "Corporate Open Source Anti-patterns" Retrieved 2015-12-26 Anti-pattern: Anti-collaborative licensing 
  162. ^ Hill, Benjamin Mako January 28, 2006 "Notes on the GPLv3" linuxcom Retrieved 2016-01-25 The GPL is one thing that almost everyone in the free and open source software communities have in common For that reason, the revision has the potential to highlight disagreements, differences in opinion, differences in business models, and differences in tactics We would be wise to remember that the potential for the GPL to hinder our ability to work together is far more dangerous than the even the most radical change textual change the FSF might suggest Above all, we must remember that our community and its goals are more important than any single license -- no matter how widespread 
  163. ^ McDougall, Paul 2007-07-10 "Linux Creator Calls GPLv3 Authors 'Hypocrites' As Open Source Debate Turns Nasty" informationweekcom Archived from the original on 2008-04-13 Retrieved 2015-02-12 the latest sign of a growing schism in the open source community between business-minded developers like Torvalds and free software purists 
  164. ^ Mavrogiannopoulos, Nikos 2013-03-26 "The perils of LGPLv3" gnutlsorg Retrieved 2015-11-18 LGPLv3 is the latest version of the GNU Lesser General Public License It follows the successful LGPLv21 license, and was released by Free Software Foundation as a counterpart to its GNU General Public License version 3 The goal of the GNU Lesser General Public Licenses is to provide software that can be used by both proprietary and free software This goal has been successfully handled so far by LGPLv21, and there is a multitude of libraries using that license Now we have LGPLv3 as the latest, and the question is how successful is LGPLv3 on this goal In my opinion, very little If we assume that its primary goal is to be used by free software, then it blatantly fails that 
  165. ^ 2013-03-14 Nikos Mavrogiannopoulos nmav@gnutlsorg COPYINGLESSER, README: gnutls 3110 is LGPLv21
  166. ^ Nikos Mavrogiannopoulos 2012-12-18 "gnutls is moving" Retrieved 2012-12-11 
  167. ^ Rosen, Lawrence 2007 "Comments on GPLv3" Rosenlawcom Retrieved 22 August 2014 
  168. ^ Ronacher, Armin 2013-07-23 "Licensing in a Post Copyright World" lucumrpocooorg Retrieved 2015-11-18 The License Compatibility Clusterfuck - When the GPL is involved the complexities of licensing becomes a non fun version of a riddle So many things to consider and so many interactions to consider And that GPL incompatibilities are still an issue that actively effects people is something many appear to forget For instance one would think that the incompatibility of the GPLv2 with the Apache Software License 20 should be a thing of the past now that everything upgrades to GPLv3, but it turns out that enough people are either stuck with GPLv2 only or do not agree with the GPLv3 that some Apache Software licensed projects are required to migrate For instance Twitter's Bootstrap is currently migrating from ASL20 to MIT precisely because some people still need GPLv2 compatibility Among those projects that were affected were Drupal, WordPress, Joomla, the MoinMoin Wiki and others And even that case shows that people don't care that much about licenses any more as Joomla 3 just bundled bootstrap even though they were not licenses in a compatible way GPLv2 vs ASL 20 The other traditional case of things not being GPL compatible is the OpenSSL project which has a license that does not go well with the GPL That license is also still incompatible with the GPLv3 The whole ordeal is particularly interesting as some not so nice parties have started doing license trolling through GPL licenses 
  169. ^ Are you sure you want to use the GPL by Armin Ronacher 2009

External links

  • GNU General Public License version 3
  • GNU General Public License v20—This version is deprecated by the FSF but is still used by many software projects, including Linux kernel and GNU packages
  • GNU General Public License v10—This version is deprecated by the FSF
  • The Emacs General Public License, a February 1988 version, a direct predecessor of the GNU GPL
  • History of the GPL by Li-Cheng Tai, July 4, 2001
  • A Practical Guide to GPL Compliance Covers GPLv2 and v3—from the Software Freedom Law Center
  • A paper on enforcing the GPL
  • Frequently Asked Questions about the GPL
  • GPL, BSD, and NetBSD – why the GPL rocketed Linux to success by David A Wheeler
  • GNU General Public License and Commentaries, edited by Robert Chassell
  • List of presentation transcripts about the GPL and free software licenses by the FSFE
  • Make Your Open Source Software GPL-Compatible Or Else by David A Wheeler—Why a GPL-compatible license is important to the health of a project 7 April 2004
  • The Labyrinth of Software Freedom BSD vs GPL and social aspects of free licensing debate, by Nikolai Bezroukov

gnu general public license, gnu general public license (gpl), gnu general public license download, gnu general public license explained, gnu general public license software, gnu general public license v3, gnu general public license version 2, gnu general public license version 2 june 1991, gnu general public license version 3, gnu general public license version 3.0 (gplv3)

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