If the copyleft software becomes part of a larger software product, and the licensee distributes that product, it has to distribute the whole thing as. Open source licenses are licenses that comply with the open source definition in brief, they allow software to be freely used, modified, and shared. Yet, many foss licences, like the apache license, and all free software. The mit license is also compatible with many copyleft licenses, such as the gnu general public license gpl. We provide below is a little explanation of copyleft versus non. There are variations, of coursethe lgpl, for example, is a weak copyleft. With open source software, there are two main types of licenses.
In the gnu project, the specific distribution terms that we use for most software are contained in the gnu general public license. It is a permissive license, meaning that it allows programmers to put the code in proprietary software on the condition that the license is given with that software, and gplcompatible, meaning that the gpl permits programmers to combine and redistribute it with software that uses. This means that any software that is written based on any gpl component must be released as open source. The mit license is a free software license created by the mit massachusetts institute of technology. A simple permissive software license used by the massachusetts institute of technology many times over. Mit licensed software can be relicensed as gpl software, and integrated wit. Apr 16, 2020 by 2019, 33 percent of the software in the whitesource data set relied on copyleft licenses while 67 percent of the software favored a permissive opensource license. Why dash uses the mit license and not a copyleft gpl. Various licenses and comments about them gnu project. Mit licensed software can be integrated into gpl software, but not the other way around. Various licenses and comments about them gnu project free. Jan 26, 2018 the bestknown copyleft license is the general public license, or gpl, from the free software foundation. Since our products are commercial and not free our code is closed, we only integrate third party software that have noncopyleft license. This license is sometimes referred to as the 3clause bsd license.
The open source initiative osi is one such organization keeping a list of opensource licenses. A stronger copyleft license is the agpl which requires the publishing of the source code also for the usage case software as a service, see also the term sometimes used, service as a software substitute saass 30 31 32 e. Nonjudgmental guidance on choosing a license for your open source project. Nonjudgmental guidance on choosing a license for your open source. It is compatible because it can be relicensed under other licenses. Mit license a short and simple permissive license with conditions only requiring preservation of and license notices. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files the software, to deal in the. Thats why we reverse the name, changing into copyleft. Permissive opensource software licenses continue to gain popularity at the expense of copyleft licenses, according to a forthcoming report. There are 3 bsd licenses, but only two accepted and recommended by the open source initiative and the fsf.
Permissive software licenses are now more popular than gpl or copyleft licenses. The gnu free documentation license is another example of a copyleft non software license. Many other copyleft licenses exist with smaller adoption footprints. Such software must usually be passed on with a copyleft license that requires successive users to accept and transmit copyleft and mandates that any modifications or improvements to the copylefted software be likewise transmitted under copyleft. Oct 16, 2019 instead, copyleft license rules require all derivative works to be subject to the original license. Examples include the gnu allpermissive license, mit license, bsd licenses, apple public source license and apache license. The gnu general public license is often called the gnu gpl for short. Jun 24, 2006 most copylefted software is issued under the gnu general public license gpl, which was the first copyleft license and by far the most commonly used license for free software. If you choose to use or modify code released under this license, it must be provided under the same license. Nov 21, 2014 as software developers and publishers, when it comes to integrating third party software, we have to look carefully at the license. Why dash uses the mit license and not a copyleft gpl license. The content on this website, of which is the author, is licensed under a creative commons attribution 4. A permissive software license, sometimes also called bsdlike or bsdstyle license, is a free software license with minimal requirements about how the software can be redistributed.
Copyleft itself probably began in the work of mit computer expert richard stallman. Nov 09, 2019 supporting a strong copyleft, the gpl is probably the most protective free software license. The mit license is a permissive free software license originating at the massachusetts institute of technology mit in the late 1980s. There are 3 bsd licenses, but only two accepted and recommended by the open. Mit license simple english wikipedia, the free encyclopedia. Software licensing can be a personal or philosophical choice, and were not looking to incite controversy. Free software is software whose source code is freely available to anyone to use for any purpose, including studying, copying, modifying, extending and giving away. While the gpl family are the most popular copyleft licenses, they are by no means the only ones. The disadvantage is that anyone can take software licensed under mit, change the branding, and sell it as proprietary software. They can essentially license their fork how they like. Fsfs free software and osis opensource licenses together are called foss licenses.
The jquery project uses a version of the mit license. Mar 25, 2015 permission is hereby granted, free of charge, to any person or organization obtaining a copy of the software and accompanying documentation covered by this license the software to use, reproduce, display, distribute, execute, and transmit the software, and to prepare derivative works of the software, and to permit thirdparties to whom the. Gpl, the copyleft license we talked about here, is good if you want to ensure that all the downstream developers will be open source, but this may discourage adoption of your code. The mit license, which you chose to license your work under, doesnt prevent anyone downstream from changing the license, nor from changing the license of a derivative unlike a copyleft license such as the gpl. These projects will hopefully be licensed if you havent got a license on your opensource project, youre doing it wrong, to ensure that your contributions. Notice that the popular licenses featured on the home page gnu gplv3 and mit fall within. The revised bsd license3 clause, and the simplified bsd. Furthermore, mit licenses dont explicitly include a patent license grant. Free software licenses can be divided into two broad categories. Open source licenses grant permission for anybody to use, modify, and share licensed software for any purpose, subject to conditions preserving.
Comparison of free and opensource software licences wikipedia. Jan 23, 2020 the gpl was a trailblazer at the start of the open source revolution and is a prime example of the copyleft or viral license. The mit license is short, clear, and easy to understand. Copyleft software can only be used to create other copyleft software unless a company owns the copyleft license and will sell it to others for commercial works which still leads to a leaf on the evolutionary tree. Commercializing software released under an mit license is more challenging. The mit license is a free software license that was created at the massachusetts institute of technology mit. The free software foundation fsf maintains a list of what it considers free. Not formally accepted by osi, and also offered in a windowsonly lpl variant. The use of software licenses for non software work is generally discouraged.
If youre looking for a reference table of every license on, see the appendix. Its simplicity is the reason behind its high adoption rate among developers. Licensed works, modifications, and larger works may be distributed under different terms and without source code. Gnu project the gnu operating system and the free software. The mozilla public license and the eclipse public license are also very popular. Gnu general public license v3 gpl3 371653 code license managed by kevin. Something it can be praised or criticized for depending your point of view.
The core concept behind the gpl being any derivative work must be released under the gpl too. Without an open source license, the software component is unusable by others. Some people call this license the mit license, but that term is misleading, since mit has used many licenses for software. The first is called the gnu general public license the gpl.
As a permissive license, it puts only very limited restriction on reuse and has, therefore, reasonable license compatibility. Requires all contributed code to be returned to the community. The mit license is compatible with many copyleft licenses, such as the gnu general public license. Which license to use a great many developers, myself included, believe that it is important to spend at least some time contributing to opensource software projects. Copyleft is a general concept, and you cant use a general concept directly. A common business model involves licensing the software as opensource, and offering. Proprietary software developers use to take away the users freedom. When users incorporate a component licensed under one of the gpl licenses, they must release its source code, as well as the rights to modify and distribute the entire code. Questions about the in a license should be directed to the license steward. Whitesource concluded that use of permissive opensource licenses continues to rise, while usage of copyleft licenses, and the gplfamily in particular, continues to decrease. Weak copyleft allows liberal mixing with proprietary software. A data scientists guide to open source licensing towards. The problem for traditional proprietary software distributors gets worse from there.
Notice that the popular licenses featured on the home page gnu gplv3 and mit fall within this spectrum. Should you use a gnu gpl or mit open source license. It allows you to do just about anything you want with the software. So if you use a library in a project, the rest of the project doesnt need to be distributed under that license, but the library does. A common business model involves licensing the software as opensource, and offering proprietary extensions built on top of that software. The following licenses are sorted by the number of conditions, from most gnu agplv3 to none unlicense. An open source license protects contributors and users. Open source licenses grant permission for anybody to use, modify, and share licensed software for any purpose, subject to conditions preserving the provenance and openness of the software. The osi recommends a mix of permissive and copyleft licences, the apache license 2. It is a lax, permissive noncopyleft free software license, compatible with the gnu gpl. According to research by white source, the most popular permissive licenses are mit and apache 2. And if you make modifications to the code under mspl, those modifications must also follow that license.
Basically, you can do whatever you want with software licensed under the mit license only if you add a copy of the original mit license and notice to it. This means that developers cannot make patent or claims on the original software. The most wellknown free software license that uses strong copyleft is the gnu general public license. As a permissive license, it puts only very limited restriction on reuse and has, therefore, high license compatibility. Dec 21, 2018 the reason is that this software can be used to create other liberally licensed, copyleft, or commercially licensed software. This is a comparison of free and opensource software licences. According to sims, bsd is included in mac os, ios as well as many wellknown projects used with the android operating system.