Whenever changes are made under gpl license, source codes are required and changes must also be licensed under gpl, while lgpl may allow nongpl programs to link to. Gpl, gnu lesser general public license lgpl, and the mozilla public license. On selling exceptions to the gnu gpl free software. The project is open source, so i want others to make use of it as well, but i dont want them to create derivative works with closedsource licenses. In contrast to lgpl, gpl requires that you provide the code for all changes made to the software.
The software freedom law center provides practical advice for developers about including permissively licensed source. If you modify the software, you still have to give back the source code, but you are allowed to link it with proprietary stuff without giving the. Ive dealt with the gpl case, which is the ontopic bit. Open source licenses explained in this detailed guide. The fact that cgal is open source software does not mean that. What is the difference between gpl and lgpl licenses. Clearly, if software is released under an open source licence it is not practicable to charge for the software as your neighbour can give it away for free. That the first two are legal has no bearing on the. Some of the most popular weak copyleft licenses are. A quick guide to software licensing for the scientistprogrammer. Dual licensing schemes should code be dual licensed under the gpl and a permissive license.
Ive seen rare cases where the licensor explicitly stipulates a dual license to mean both apply simultaneously. However, the linking exception of the lgpl allows linking from an apache 2. The license was originally written by richard stallman, former head of the free software foundation fsf, for the gnu project, and grants the recipients of a computer. Is dual licensing a software that contains gpl programs. Gpl and lgpl open source licensing restrictions stack. A copyleft license permits embedding in a larger program only if the whole combined program is released under that license. A lesser general public license is used to license free software so that it can be incorporated into both free software and proprietary software, and is often referred to as the weaker sibling of gpl. This may mean multiple different software licenses or sets of licenses. The free software foundation considers the apache license, version 2. Can i dual license the whole thing under gpl gpl programs and my stuff. An updates on this issue, we have secured the agreement of all the holders to relicense libusbwin32 library as dual license. What dual licensing means in terms of computer software dps. The lgpl and gpl licenses differ with one major exception. To understand the difference between gpl and lgpl you have to understand the basic idea of open source software.
The relicensing section 4cii means that projects no longer need to duallicense with the gpl, because the artistic license itself allows redistribution of the code under the gpl or any copyleft license. Free software foundation software is covered by the gnu library general public license instead. Dual mitgpl the correct way of expressing that the module is dual licensed under a gpl v2 variant or mit license choice. This is also known as the duallicense strategy of commercial open source. A notable example is the mozilla foundations decision to implement a trilicensing model to license certain software under the mozilla public license mpl, the general public license and the lesser general public license lgpl in an effort to address the issue of incompatibility with the gpl, as pointed out by richard stallman. Multilicensing notably duallicensing is not that uncommon. Dual licensing usually refers to licensing software under both a proprietary license and an open source license, typically the gpl. For maximum flexibility if the gpl suits your project better presumably someone could leverage a portion of jquery in a larger project. The free software foundation may publish revised andor new versions of the gnu lesser general public license from time to time. Linux kernel licensing rules the linux kernel documentation. Gpl is mostly for programs while lgpl is limited to software libraries. The gnu gpl general public license covers over 50% of the free software projects including the linux kernel, busybox and many applications. In this section we explain the essence of the different licenses, as well as the rationale why we have chosen them.
The gnu general public license gnu gpl or gpl is a widelyused free software license that guarantees end users the freedom to run, study, share, and modify the software. The dual licensing model answered a need for commercial. We disclose the softwares source codes so that you may get. The most widespread use of gpl is in reference to the gnu gpl, which is commonly abbreviated simply as gpl when it is understood that the term refers. Dual licensing emerged as an open source business model in the early 2000s, and it typically refers to the release of a software component under two licenses simultaneously. Prefixes may be used to indicate the number of licenses used, e. Lgpl may make your code more useful to others, while still protecting your work. Most gpl version 2 software is actually licensed as gpl version 2 or any later version, or. The gpl the gnu general public license the most popular copyleft licence, sometimes gets a. Short for general public license, the license that accompanies some open source software that details how the software and its accompany source code can be freely copied, distributed and modified. This license is based on gplv3 with a new requirement to ensure that users who interact with the software over a network can receive the source for that program. The difference between the gpl and the lgpl is that with the lgpl, the entire work doesnt have to have the same license.
Im currently working on an arduinocompatible software project. Revised versions of the gnu lesser general public license. Since you have access to the codes through open source software, you are permitted to make changes, improve it, and create your own twist. Ive done a lot of research on this, but im still quite confused. Track in fossa gnu lesser general public license v2. License compatibility and relicensing free software foundation. Read all the licenses that apply to the software and source code and make sure you understand them. We use only licenses that are compatible with the gnu gpl for gnu software. The commercial qt license gives you the full rights to create and distribute software on your own terms without any. What dual licensing means in terms of computer software.
The gpl licenses gplv3, gplv2, lgpl, affero gpl all contain some kind of sharealike license. The gnu general public license gnu gpl or gpl is a series of widely used free software licenses that guarantee end users the freedom to run, study, share, and modify the software. Supporting services are not the only way that an open source business can make money. Gpl is basically the legal terminology that makes open source software what it is. Lgpl allows you to use and distribute the open source software with your application without releasing the source code for your application. Various licenses and comments about them gnu project free. There are multiple variants of the gnu gpl, each with different requirements. A quick guide to software licensing for the scientist. The fsf claims that gpl v2 is incompatible with apache 2.
But they come with some requirements such as distribution of the source code, or dual licensing. The exact variant of the bsd license can only be determined via the license information in the corresponding source files. Gpllgpl software the product includes software licensed under gnu general public license gpl or gnu lesser general public license lgpl. The gnu lesser general public license lgpl is a freesoftware license published by the free software foundation fsf. If i modify code that is dual licensed under the gpl and. Among the two gpl is the basis of open source software for programmers. Dual license with gpl and a closed source license software. The gnu gpl is the most widely used free software license and has a strong copyleft requirement.
Selling exceptions depends fundamentally on using a copyleft license, such as the gnu gpl, for the free software release. Gpl is a copyleft license so it requires derivative works to be released under the same license and programs linked with a library released under the gpl must also be released under the gpl. Furthermore, if you own the rights to something, you can distribute it under both the gpl and in the app store duallicensing is not new. 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. Gnu general public license, version 3 spdx short identifier. In order to comply with the terms of the gpl the respective tplink group company which offer respective software for download or is responsible for the distribution of products that contain respective code, offers, where applicable, by itself or with the support of third parties e. It also contains a patent license and retaliation clause which is designed to prevent patents including patent trolls from encumbering the software project. Difference between gpl and lgpl difference between. Qt contains also thirdparty code that is licensed under specific opensource licenses from the original authors.
The free software foundation today released the second discussion draft of the gnu affero general public license gnu agpl. And although how a librarys author can make hisher software available under lgpl is ontopic for this site, how someone else can take that and work it into a proprietary product isnt. Yes, if you like, you may ignore the offer to receive the software under the gpl and instead receive it only under the lgpl. In most cases when open source code is licensed under two licenses, the licensee gets to select which one applies to their use. Anything statically linked to the library can only be redistributed under lgpl, but applications that use the library. Qt for application development lets you create applications for desktop and mobile platforms. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Difference between gpl and lgpl compare the difference. The lgpl is similar to the gpl, but is more designed for software libraries where you want to allow nongpl applications to link to your library and utilise it. In general, if the option is a gplmit dual license you would usually pick gpl if you want to create an open source derivative be aware, any derivative made of a gpl software must distribute both the binaries and the source code. Software can become incompatible with secondary licenses in one of two ways. When distributing derived works, the source code of the work must be made available under the same license.
Cgal is distributed under a dual license scheme, that is under the gpl lgpl open source license, as well as under commercial licenses cgal consists of different parts covered by different open source licenses. Some free software licenses dont establish an obligation of licensing derivative work in the same terms of the original work license. Oracle elects to use only the gnu lesser general public license version 2. It contains all the qt apis and the qt creator ide for seamless crossplatform development qt for application development is duallicensed under commercial and open source licenses. Gpl requires you to release the source code of your application if you choose to use and distribute the gpl licensed open source software with your application. Apache 2 software can therefore be included in gplv3 projects, because the gplv3 license accepts our software into gplv3 works. The software must not be incompatible with secondary licenses. Qt licensed under the gnu lesser general public license lgpl version 3 is appropriate for the development of qt applications provided you can comply with the terms and conditions of the gnu lgpl version 3 or gnu gpl version 3. Multilicensing is the practice of distributing software under two or more different sets of terms and conditions. You may copy, distribute and modify the software provided that you state modifications and license them under lgpl2. Dual licensing emerged as an open source business model in the early 2000s, and it typically refers to the release of a software component.
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