52-667: The Academic Free License ( AFL ) is a permissive free software license written in 2002 by Lawrence E. Rosen , a former general counsel of the Open Source Initiative (OSI). The license grants similar rights to the BSD , MIT , UoI/NCSA and Apache licenses – licenses allowing the software to be made proprietary – but was written to correct perceived problems with those licenses. The AFL: The Free Software Foundation consider all AFL versions up to and including 3.0 as incompatible with
104-590: A copyleft license and another license is often only a one-way compatibility, making the copyleft license (GPL, and most other copyleft licenses) incompatible with proprietary commercial licenses, as well as with many non-proprietary licenses. This "one-way compatibility" characteristic has been criticized by the Apache Foundation , which licenses under the more permissive Apache license , such non-copyleft licenses being often less complicated and making for better license compatibility. An example of
156-522: A BSD conference in 1999. It is a word play on copyright , copyleft and copy center . We call them “pushover licenses” because they can't say “no” when one user tries to deny freedom to others.." In the Free Software Foundation 's guide to license compatibility and relicensing, Richard Stallman defines permissive licenses as "pushover licenses", comparing them to those people who "can't say no", because they are seen as granting
208-401: A combined work including copyleft licensed components (which have a viral property leading potentially to a derived work ), proper isolation/separation needs to be maintained. With individually licensed source code files, multiple non-reciprocal licenses (such as permissive licenses or own proprietary code) can be separated, while the combined compiled program could be re-licensed (but that
260-709: A combined work or derivative work of the GPLed kernel—is ambiguous and controversial. In 2015, the CDDL to GPL compatibility question reemerged when the linux distribution Ubuntu announced that it would include OpenZFS by default. In 2016, Ubuntu announced that a legal review resulted in the conclusion that it is legally safe to use ZFS as a binary kernel module in Linux. Others accepted Ubuntu's conclusion; for instance lawyer James E.J. Bottomley argued "a convincing theory of harm" cannot be developed, making it impossible to bring
312-533: A derivative work of the Linux kernel, and announced their intent to achieve clarity in this question, even by going to court. On October 8, 2015, Creative Commons concluded that the CC BY-SA 4.0 is inbound compatible with the GPLv3. The Creative Commons Licenses are widely used for content, but not all combinations of the seven recommended and supported licenses are compatible with each other. Additionally, this
364-490: 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
416-542: A license that has excellent compatibility with other FOSS licenses is the Artistic License 2.0, due to its re-licensing clause which allows redistribution of the source code under any other FOSS license. You may Distribute your Modified Version as Source (either gratis or for a Distributor Fee, and with or without a Compiled form of the Modified Version) [...] provided that you do at least ONE of
468-450: A permissive software license as a "non- copyleft license that guarantees the freedoms to use, modify and redistribute". GitHub 's choosealicense website describes the permissive MIT license as "[letting] people do anything they want with your code as long as they provide attribution back to you and don't hold you liable ." California Western School of Law 's newmediarights.com defined them as follows: "The 'BSD-like' licenses such as
520-544: A proprietary license, turning it into proprietary software . Many copyleft licenses explicitly allow relicensing under some other copyleft licenses. Permissive licenses are (with minor exceptions) compatible with everything, including proprietary licenses; there is thus no guarantee that all derived works will remain under a permissive license. License compatibility can be defined around the concepts of "collective/combined/aggregated work" and " derivative work ". The first " collective work " license compatibility definition allows
572-525: A restriction that says a redistributor cannot add more restrictions. Examples include the CDDL and MsPL . However such restrictions also make the license incompatible with permissive free-software licenses. While they have been in use since the mid-1980s, several authors noted an increase in the popularity of permissive licenses during the 2010s. As of 2015, the MIT License , a permissive license,
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#1732797802533624-489: A right to "deny freedom to others." The Foundation recommends pushover licenses only for small programs, below 300 lines of code, where "the benefits provided by copyleft are usually too small to justify the inconvenience of making sure a copy of the license always accompanies the software". License compatibility License compatibility is a legal framework that allows for pieces of software with different software licenses to be distributed together. The need for such
676-427: A stronger isolation is required. This can be achieved by separating the programs by an own process and allowing communication only via binary ABIs or other indirect means. Examples are Android 's kernel space -to- user space separation via Bionic , or Linux distros which have proprietary binary blobs included despite having a strong copyleft kernel . While for some domains agreement exists if an isolation
728-478: Is a free-software license which instead of copyleft protections, carries only minimal restrictions on how the software can be used, modified, and redistributed, usually including a warranty disclaimer . Examples include the GNU All-permissive License , MIT License , BSD licenses , Apple Public Source License and Apache license . As of 2016, the most popular free-software license is
780-565: Is distributed exclusively under the terms of GPLv2. The Free Software Foundation-recommended GNU Free Documentation License is incompatible with the GPL license, and text licensed under the GFDL cannot be incorporated into GPL software. Therefore, the Debian project decided, in a 2006 resolution, to license documentation under the GPL. The FLOSS Manuals foundation followed Debian in 2007. In 2009,
832-454: Is not required). Such source-code file separation is too weak for copyleft/reciprocal licenses (such as the GPL), as they then require the complete work to be re-licensed under the reciprocal license as being derivative. A slightly stronger approach is to have separation at the linking stage with binary object code ( static linking ), where all the components of the resulting program are part of
884-537: Is often impossible, due to the many contributors involved, the Mozilla re-licensing project assumes that achieving 95% is enough for the re-licensing of the complete code base. Others in the FOSS domain, such as Eric S. Raymond , came to different conclusions regarding the requirements for re-licensing of an entire code base. An early example of a project that successfully re-licensed for license incompatibility reasons
936-461: Is often only a one-way directional compatibility, requiring a complete work to be licensed under the most restrictive license of the parent works. JSON developer Douglas Crockford , inspired by the words of then President Bush, formulated the "evil-doers" JSON license ("The Software shall be used for Good, not Evil.") This subjective and moral license clause led to license incompatibility problems with other open source licenses , and resulted in
988-655: Is problematic is the CDDL licensed ZFS file system with the GPLv2 licensed Linux kernel . Despite that both are free software under a copyleft license, ZFS is not distributed with most linux distros like Debian (but is distributed with FreeBSD ) as the CDDL is considered incompatible with the GPL'ed Linux kernel, by the Free Software Foundation and some parties with relations with the FSF. The legal interpretation—of if and when this combination constitutes
1040-483: Is suitable, there are domains in dispute and up to now untested in court. For instance, in 2015 the SFC sued VMware in an ongoing dispute whether loadable kernel modules (LKM's) are derivative works of the GPL'd Linux kernel or not. Licenses common to free and open-source software (FOSS) are not necessarily compatible with each other, and this can make it legally impossible to mix (or link ) open-source code if
1092-555: Is the Mozilla project and their Firefox browser . The source code of Netscape 's Communicator 4.0 browser was originally released in 1998 under the Netscape Public License / Mozilla Public License but was criticised by the Free Software Foundation (FSF) and OSI for being incompatible with the GNU General Public License (GPL). Around 2001 Time Warner , exercising its rights under
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#17327978025331144-448: Is the most popular free software license, followed by GPLv2 . A "permissive" license is simply a non-copyleft open source license. Sometimes the word "permissive" is considered too ambiguous, because all free software licenses are "permissive", in the sense that they all allow to modify and redistribute the source code. In most cases the real opposition is between copyleft licenses and non-copyleft ones, thus some authors prefer to use
1196-586: The 4-clause BSD license , the PHP License , and the OpenSSL License , have clauses requiring advertising materials to credit the copyright holder, which made them incompatible with copyleft licenses. Popular modern permissive licenses, however, such as the MIT License , the 3-clause BSD license and the zlib license , don't include advertising clauses and are generally compatible with copyleft licenses. Some licenses do not allow derived works to add
1248-602: The Creative Commons Attribution-ShareAlike as its main license, in addition to the previously used GFDL , so as to have improved license compatibility with the greater free content ecosystem. Another interesting case was Google 's re-licensing of GPLv2-licensed Linux kernel header files to the BSD license for their Android library Bionic . Google claimed that the header files were clean of any copyright-able work, reducing them to non-copyrightable "facts", and thus not covered by
1300-716: The GNU GPL . though Eric S. Raymond (a co-founder of the OSI) contends that AFL 3.0 is GPL compatible. In late 2002, an OSI working draft considered it a "best practice" license. In mid-2006, however, the OSI's License Proliferation Committee found it "redundant with more popular licenses", specifically version 2 of the Apache Software License . Permissive free software license A permissive software license , sometimes also called BSD-like or BSD-style license,
1352-435: The "derived work" combined from code under various licenses as whole is applied to the copyleft license. License compatibility: The characteristic of a license according to which the code distributed under this license may be integrated into a bigger software that will be distributed under another license . [emphasis added] A combined work consists of multiple differently-licensed parts (avoiding relicensing ). To achieve
1404-498: The BSD, MIT and Apache licenses are extremely permissive, requiring little more than attributing the original portions of the licensed code to the original developers in your own code and/or documentation." Copyleft licenses generally require the reciprocal publication of the source code of any modified versions under the original work's copyleft license. Permissive licenses, in contrast, do not try to guarantee that modified versions of
1456-547: The GPL. This interpretation was challenged by Raymond Nimmer, a law professor at the University of Houston Law Center . Apps and drivers of Android, which provide an increasing amount of Android's functionality, have been gradually relicensed from permissive to proprietary licenses. In 2014, the FreeCAD project changed their license from GPL to LGPLv2, due to GPLv3/GPLv2 incompatibilities. Also in 2014, Gang Garrison 2
1508-456: The JSON license not being a free and open-source license. Sometimes projects wind up with incompatible licenses, and the only feasible way to solve it is the re-licensing of the incompatible parts. Re-licensing is achieved by contacting all involved developers and other parties and getting their agreement for the changed license. While in the free and open-source domain achieving 100% agreement
1560-520: The Modified Version, and of any works derived from it, be made freely available in that license fees are prohibited but Distributor Fees are allowed. [emphasis added] The Common Development and Distribution License (CDDL)—a weak copyleft license in-between the GPL license and BSD / MIT permissive licenses —tries to address license compatibility problems by permitting, without re-licensing,
1612-600: The Netscape Public License, and at the request of the Mozilla Foundation, re-licensed all code in Mozilla that was under the Netscape Public License (including code by other contributors) to an MPL 1.1/GPL 2.0/ LGPL 2.1 tri-license , thus achieving GPL-compatibility. The Vorbis library was originally licensed as LGPL , but in 2001, with the endorsement of Richard Stallman , the license
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1664-579: The VLC library, from the GPLv2 to the LGPLv2, to achieve better compatibility. In July 2013, the software re-licensed under the Mozilla Public License , the VLC application would then be resubmitted to the iOS App Store . The Free Software Foundation's GNU Free Documentation License version 1.2 is not compatible with the widely used Creative Commons Attribution-ShareAlike license, which
1716-496: The Wikimedia Foundation switched from the GFDL to a Creative Commons CC-BY-SA license as the main license for their projects. Responsible AI Licenses (or RAILs) are generally not compatible with the GPL. This is because RAILs include "use restrictions" that limit the ways users can make use of the materials licensed under RAILs, whereas the GPL prohibits such restrictions. Another case where GPL compatibility
1768-599: The case to court. Eben Moglen , co-author of the GPLv3 and founder of the SFLC , argued that while the letters of the GPL might be violated the spirit of both licenses is adhered to, which would be the relevant issue in court. On the other hand, Bradley M. Kuhn and Karen M. Sandler , from the Software Freedom Conservancy , argued that Ubuntu would violate both licenses, as a binary ZFS module would be
1820-507: The components have different licenses. For example, software that combined code released under version 1.1 of the Mozilla Public License (MPL) with code under the GNU General Public License (GPL) could not be distributed without violating one of the terms of the licenses; this despite both licenses being approved by both the Open Source Initiative and the Free Software Foundation . License compatibility between
1872-415: The final users might not be developers at all, and in this case copyleft licenses offer them the everlasting right to access a software as free software, ensuring that it will never become closed source – while permissive licenses offer no rights at all to non-developer final users, and software released with a permissive license could theoretically become from one day to another a closed source malware without
1924-533: The following: […] (c) allow anyone who receives a copy of the Modified Version to make the Source form of the Modified Version available to others under (i) the Original License or (ii) a license that permits the licensee to freely copy, modify and redistribute the Modified Version using the same licensing terms that apply to the copy that the licensee received, and requires that the Source form of
1976-400: The incompatibility. However, code under the later licenses can be combined with code licensed under GPL version 2 or later. Most software released under GPLv2 allow you to use the terms of later versions of the GPL as well, and some have exception clauses that allow combining them with software that is under different licenses or license versions. The Linux kernel is a notable exception that
2028-516: The mixing of CDDL-licensed source-code files with source-code files under other licenses by providing that the resulting binary can be licensed and sold under a different license as long as the source code is still available under CDDL. To minimize license proliferation and license incompatibilities in the FOSS ecosystem, some organizations (the Free Software Foundation, for instance) and individuals (David A. Wheeler), argue that compatibility with
2080-400: The new combination would have the GPL applied to the whole (but the other license would not so apply). Copyleft software licenses are not inherently GPL-compatible; even the GPLv2 license by itself is not compatible with GPLv3 or LGPLv3. If a developer tried to combine code released under either of the later GPL licenses with GPLv2 code, that would violate section 6 of GPLv2, the source of
2132-417: The permissive MIT license . The following is the full text of the simple GNU All-permissive License : Copyright <YEAR>, <AUTHORS> Copying and distribution of this file, with or without modification, are permitted in any medium without royalty, provided the copyright notice and this notice are preserved. This file is offered as-is, without any warranty. The Open Source Initiative defines
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2184-695: The public domain, on the grounds that this can be legally problematic in some jurisdictions. Public-domain-equivalent licenses are an attempt to solve this problem, providing a fallback permissive license for cases where renunciation of copyright is not legally possible, and sometimes also including a disclaimer of warranties similar to most permissive licenses. In general permissive licenses have good license compatibility with most other software licenses in most situations. Due to their non-restrictiveness, most permissive software licenses are even compatible with copyleft licenses, which are incompatible with most other licenses. Some older permissive licenses, such as
2236-420: The right to modify and exploit source code written by others and possibly incorporate it into proprietary code and make money with it (and therefore these see permissive licenses as offering them a "right"), while for other developers it might be more valuable to know that nobody will ever capitalize what has mostly been their work (and therefore these see copyleft licenses as offering them a "right"). Furthermore,
2288-426: The same process and address space . This satisfies "weak copyleft/standard reciprocal" combined works (such as LGPL licensed ones), but not "strong copyleft/strong reciprocal" combined works. While it is commonly accepted that linking ( static and even dynamic linking ) constitutes a derivative of a strong copyleft'd work, there are alternate interpretations. For combined works with "strong copyleft" modules,
2340-457: The software will remain free and publicly available, generally requiring only that the original copyright notice be retained. As a result, derivative works, or future versions, of permissively-licensed software can be released as proprietary software. Defining how liberal a license is, however, is not something easily quantifiable, and often depends on the goals of the final users. If the latter are developers, for some it might be valuable to have
2392-420: The term "non-copyleft" instead of "permissive". Berkeley had what we called "copycenter," which is "take it down to the copy center and make as many copies as you want." Copycenter is a term originally used to explain the modified BSD license , a permissive free-software license. The term was presented by computer scientist and Berkeley Software Distribution (BSD) contributor Marshall Kirk McKusick at
2444-399: The usage of variously-licensed works in a combined context: the characteristic of two (or more) licenses according to which the codes distributed under these licenses may be put together in order to create a bigger distributable software . [emphasis added] A stronger definition includes the capability to change the license. The most prominent example is the copyleft license 's demand that
2496-413: The user even knowing it. Permissive licenses offer more extensive license compatibility than copyleft licenses, which cannot generally be freely combined and mixed, because their reciprocity requirements conflict with each other. Computer Associates Int'l v. Altai used the term "public domain" to refer to works that have become widely shared and distributed under permission, rather than work that
2548-422: The widely used GPL is an important feature of software licenses. Many of the most common free-software licenses, especially the permissive licenses , such as the original MIT/X license , BSD licenses (in the three-clause and two-clause forms, though not the original four-clause form), MPL 2.0, and LGPL , are GPL-compatible . That is, their code can be combined with a program under the GPL without conflict, and
2600-588: Was a problem for Misplaced Pages , for instance. Therefore, at the request of the Wikimedia Foundation , the FSF added a time-limited section, to version 1.3 of the GFDL, that allowed specific types of websites using the GFDL to additionally offer their work under the CC BY-SA license. Following this, in June 2009, the Wikimedia Foundation migrated their projects ( Misplaced Pages , etc.) by dual licensing to
2652-471: Was changed to the less restrictive BSD license , to accelerate the library's adoption. The VLC project has a complicated license history due to license incompatibility, and in 2007 the project decided, for license compatibility, to not upgrade to the just released GPLv3 . In October 2011, after the VLC had been removed from the Apple App Store at the start of 2011, the VLC project re-licensed
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#17327978025332704-646: Was deliberately put into the public domain. However, permissive licenses are not actually equivalent to releasing a work into the public domain . Permissive licenses often do stipulate some limited requirements, such as that the original authors must be credited ( attribution ). If a work is truly in the public domain, this is usually not legally required, but a United States copyright registration requires disclosing material that has been previously published, and attribution may still be considered an ethical requirement in academia . Advocates of permissive licenses often recommend against attempting to release software to
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