+ + +

Licenses

+
+ + + +

+Published software should be free +software. To make it free software, you need to release it under +a free software license. We normally use the GNU +General Public License (GNU GPL), specifying version 3 or any +later version, but occasionally we +use other free +software licenses. We use only licenses that are compatible with +the GNU GPL for GNU software. +

+ +

+Documentation for free software should be +free documentation, so that +people can redistribute it and improve it along with the software +it describes. To make it free documentation, you need to release +it under a free documentation license. We normally use the +GNU Free Documentation License (GNU +FDL), but occasionally we use +other free +documentation licenses. +

+ +

If you've started a new project and you're not sure what license to +use, “How to +choose a license for your own work” details our +recommendations in an easy-to-follow guide. If you just want a quick +list reference, we have a page that names +our recommended +copyleft licenses.

+ +

We also have a page that discusses the BSD License Problem.

+ +
+

Evaluating Licenses

+ +

If you come across a license not mentioned in our +license list, you can ask us +to evaluate whether it is a free license. Please email a copy of the +license (and the URL where you found it) +to licensing@fsf.org. Our +licensing experts in the staff and the board of directors will review +it. If the license has some unusual conditions, they may pose +difficult philosophical problems, so we can't promise to decide +quickly.

+ +

Common Resources for our Software Licenses

+ +

We have a number of resources to help people understand and use our +various licenses:

+ + + +

The GNU General Public License

+ +

+The GNU General Public License is often called the GNU GPL for short; +it is used by most GNU programs, and by more than half of all free +software packages. The latest version is version 3. +

+ + + +

The GNU Lesser General Public License

+ +

+The GNU Lesser General Public License is used by a few (not by any means +all) GNU libraries. The latest version is version 3. +

+ + + +

The GNU Affero General Public License

+ +

+The GNU Affero General Public License is based on the GNU GPL, but has an +additional term to allow users who interact with the licensed software over +a network to receive the source for that program. We recommend that people +consider using the GNU AGPL for any software which will commonly be run +over a network. The latest version is version 3. +

+ + + +

The GNU Free Documentation License

+ +

+The GNU Free Documentation License is a form of copyleft intended +for use on a manual, textbook or other document to assure everyone +the effective freedom to copy and redistribute it, with or without +modifications, either commercially or non-commercially. The latest version +is 1.3. +

+ + + +

Exceptions to GNU Licenses

+ +

Some GNU programs have additional permissions or special exceptions + to specific terms in one of the main licenses. Since some of those + are commonly used or inspire a lot of questions on their own, we've + started collecting them on + our exceptions page.

+ +

License URLs

+ +

When linking to our licenses, it's usually best to link to the latest +version; hence the standard URLs such as +https://www.gnu.org/licenses/gpl.html have no version number. +Occasionally, however, you may want to link to a specific version of a +given license. In those situations, you can use the following links +[skip links]:

+ +
+
GNU General Public License (GPL)
+ +
GPLv3, +GPLv2, +GPLv1
+ +
GNU Lesser General Public License (LGPL)
+
LGPLv3, +LGPLv2.1
+ +
GNU Affero General Public License (AGPL)
+
GNU + AGPLv3 (The Affero General + Public License version 1 is not a GNU license, but it was + designed to serve a purpose much like the GNU AGPL's.)
+ +
GNU Free Documentation License (FDL)
+
FDLv1.3, +FDLv1.2, +FDLv1.1
+
+ +

Stable links to each license's alternative + formats are available on its respective page. Not every version of + every license is available in every format. If you need one that is + missing, please email us.

+ +

See also the old licenses page.

+ + +

Unofficial Translations

+ +

+Legally speaking, the original (English) version of the licenses is +what specifies the actual distribution terms for GNU programs and +others that use them. But to help people better understand the +licenses, we give others permission to publish unofficial translations +into other languages, provided that they follow our regulations for +unofficial translations. +

+ +

+The FSF does not approve license translations as officially valid. +The reason is that checking them would be difficult and expensive +(needing the help of bilingual lawyers in other countries). Even +worse, if an error did slip through, the results could be disastrous +for the whole free software community. As long as the translations +are unofficial, they can't do any legal harm.

+ +

To underscore the fact that these translations are not officially +valid, we do not publish translations. To make that clear, we don't +post them on gnu.org, or on other GNU and FSF web sites; we only link +to them.

+ + + +

Verbatim Copying and Distribution

+ +

The standard copyright terms for GNU web pages is now the Creative +Commons Attribution-NoDerivs 4.0 International License. It used to +be (and for a few pages still is):

+ +

Verbatim +copying and distribution of this entire article are permitted worldwide, +without royalty, in any medium, provided this notice is +preserved.

+ +

Please note the following commentary about this +“verbatim license” by Eben Moglen:

+ +

+“Our intention in using the phrase ‘verbatim copying in +any medium’ is not to require retention of page headings and +footers or other formatting features. Retention of weblinks in both +hyperlinked and non-hyperlinked media (as notes or some other form of +printed URL in non-HTML media) is required.” +

+ +

List of Free Software Licenses

+ +
    +
  • + List of Free Software Licenses + +

    If you are contemplating writing a new license, please contact the +FSF by writing to <licensing@fsf.org>. The +proliferation of different free software licenses means increased work +for users in understanding the licenses; we may be able to help you +find an existing Free Software license that meets your needs. +

    + +

    +If that isn't possible, if you really need a new license, with our +help you can ensure that the license really is a Free Software license +and avoid various practical problems. +

    + +
  • +
+ + +

What Is Copyleft?

+ +

+Copyleft is a general +method for making a program free +software and requiring all modified and extended versions of the +program to be free software as well. +

+ +

+The simplest way to make a program free is to put it in the +public +domain, uncopyrighted. This allows people to share the program +and their improvements, if they are so minded. But it also allows +uncooperative people to convert the program into +proprietary +software. They can make changes, many or few, and distribute the +result as a proprietary product. People who receive the program in +that modified form do not have the freedom that the original author +gave them; the middleman has stripped it away. +

+ +

+In the GNU project, our aim is +to give all users the freedom to redistribute and change GNU +software. If middlemen could strip off the freedom, we might have +many users, but those users would not have freedom. So instead of +putting GNU software in the public domain, we “copyleft” +it. Copyleft says that anyone who redistributes the software, with or +without changes, must pass along the freedom to further copy and +change it. Copyleft guarantees that every user has freedom. +

+ +

+Copyleft also provides an +incentive +for other programmers to add to free software. +Important free programs such as the GNU C++ compiler exist +only because of this. +

+ +

+Copyleft also helps programmers who want to contribute +improvements to +free software get permission to +do that. These programmers often work for companies or universities +that would do almost anything to get more money. A programmer may +want to contribute her changes to the community, but her employer may +want to turn the changes into a proprietary software product. +

+ +

+When we explain to the employer that it is illegal to distribute the +improved version except as free software, the employer usually decides +to release it as free software rather than throw it away. +

+ +

+To copyleft a program, we first state that it is copyrighted; then +we add distribution terms, which are a legal instrument that gives +everyone the rights to use, modify, and redistribute the program's +code or any program derived from it but only if the +distribution terms are unchanged. Thus, the code and the freedoms +become legally inseparable. +

+ +

+Proprietary software developers use copyright to take away the users' +freedom; we use copyright to guarantee their freedom. That's why we +reverse the name, changing “copyright” into +“copyleft”. +

+ +

+Copyleft is a general concept; there are many ways to fill in the +details. In the GNU Project, the specific distribution terms that we +use are contained in the GNU General Public License, the GNU Lesser +General Public License and the GNU Free Documentation License. +

+ +

+The appropriate license is included in many manuals and in each GNU +source code distribution. +

+ +

+The GNU GPL is designed so that you can easily apply it to your own +program if you are the copyright holder. You don't have to modify the +GNU GPL to do this, just add notices to your program which refer +properly to the GNU GPL. Please note that you must use the +entire text of the GPL, if you use it. It is an integral whole, and +partial copies are not permitted. (Likewise for the LGPL, AGPL, and FDL.) +

+ +

+Using the same distribution terms for many different programs makes it +easy to copy code between various different programs. Since they all +have the same distribution terms, there is no need to think about +whether the terms are compatible. The Lesser GPL includes a +provision that lets you alter the distribution terms to the ordinary +GPL, so that you can copy code into another program covered by the GPL. +

+ +

Licenses for Other Types of Works

+ +

+We believe that published software and documentation should be +free software and free documentation. +We recommend making all sorts of educational and reference works free +also, using free documentation licenses such as the +GNU Free Documentation License (GNU FDL). +

+ +

For essays of opinion and scientific papers, we recommend +either the Creative +Commons Attribution-NoDerivs 3.0 United States License, or the +simple “verbatim copying only” license stated above.

+ +

+We don't take the position that artistic or entertainment works must +be free, but if you want to make one free, we recommend +the Free Art +License.

+
+ +