The Q Public License (QPL) is a non-

copyleft Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, ''freedoms'' refers to the use of the work for any purpose, ...

license, created by the company

Trolltech Qt Group Plc (Qt is pronounced "cute") is a software company headquartered in Espoo, Finland. It was formed following the acquisition of Qt by Digia, but was later spun off into a separate, publicly traded company. The company oversees the de ...

for its

free software Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...

edition of the Qt toolkit and framework. It was used until Qt 3.0, until version 4.0 was released under the

Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985. The organisation supports the free software movement, with the organization's preference for software being distributed ...

's (FSF)

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

(GPL) version 2. It fails the

Debian Free Software Guidelines ''The Open Source Definition'' (OSD) is a policy document published by the Open Source Initiative. Derived from the Debian Free Software Guidelines written by Bruce Perens, the definition is the most common standard for open-source software. ...

, used by several

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

distributions, though it qualifies for the FSF's Free Software Definition; however, it is incompatible with the FSF's GPL, meaning that products derived from code under both the GPL and the QPL cannot be redistributed.

History

KDE KDE is an international free software community that develops free and open-source software. As a central development hub, it provides tools and resources that enable collaborative work on its projects. Its products include the KDE Plasma gra ...

, a

desktop environment In computing, a desktop environment (DE) is an implementation of the desktop metaphor made of a bundle of programs running on top of a computer operating system that share a common graphical user interface (GUI), sometimes described as a graphi ...

for

, is based on Qt. Only the free open source edition of Qt was covered by the QPL; the commercial edition, which is functionally equal, is under a pay-per-use license and could not be freely distributed. Meanwhile, the

and authors of the GPL objected to the QPL as it was a non-copyleft license incompatible with the GPL. As KDE grew in popularity, the

free software community The free software movement is a social movement with the goal of obtaining and guaranteeing certain freedoms for software users, namely the freedoms to run, study, modify, and share copies of software. Software which meets these requirements, ...

urged Trolltech to license Qt under the GPL to ensure that it would remain free software forever and could be used and developed by commercial third parties. Eventually, under pressure, Trolltech dual-licensed the free edition of Qt 2.2 for use under the terms of the GPL or the QPL.

Adoption

Other projects that have adopted the Q Public License, sometimes with a change in the choice of jurisdiction clause, include: * LibreSource is a versatile collaborative platform provided by artenum and dedicated to collaborative software development * Jpgraph is a graph generation tool written in PHP that dynamically produces charts and graphs as image files for presentation on websites. *

Hercules Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the Gr ...

, a software implementation of the

System/370 The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the IBM System/360, System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migrati ...

ESA/390 IBM Enterprise Systems Architecture is an instruction set architecture introduced by IBM as Enterprise Systems Architecture/370 (ESA/370) in 1988. It is based on the IBM System/370-XA architecture. It extended the dual-address-space mechanis ...

, and

z/Architecture z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit complex instruction set computer (CISC) instruction set architecture, implemented by its mainframe computers. IBM introduced its first z/Architecture ...

mainframe computer architectures. On January 1, 2024, Jay Maynard announced a proposal to relicense Hercules under an

MIT License The MIT License is a permissive software license originating at the Massachusetts Institute of Technology (MIT) in the late 1980s. As a permissive license, it puts very few restrictions on reuse and therefore has high license compatibility. Unl ...

on July 1, 2024. however this proposal was rejected as it did not have the unanimous approval of all of the copyright holders. * Tgif switched from a free-of-charge non-commercial license to the Q Public License. Prior projects using the Q Public License include: * The

OCaml OCaml ( , formerly Objective Caml) is a General-purpose programming language, general-purpose, High-level programming language, high-level, Comparison of multi-paradigm programming languages, multi-paradigm programming language which extends the ...

compiler and related tools from Projet Cristal at

INRIA The National Institute for Research in Digital Science and Technology (Inria) () is a French national research institution focusing on computer science and applied mathematics. It was created under the name French Institute for Research in Comp ...

. Since April 2016, OCaml is released under the

GNU Lesser General Public License The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

version 2.1 with linking exception. * Computational Geometry Algorithms Library ( CGAL) for versions 3.x. The CGAL

library A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...

is released under

(GPL) and

(LGPL) since CGAL version 4.0 (March 2012). The

Debian Debian () is a free and open-source software, free and open source Linux distribution, developed by the Debian Project, which was established by Ian Murdock in August 1993. Debian is one of the oldest operating systems based on the Linux kerne ...

project rejects software covered by solely QPL (and not dual licensed with something else like the GPL) because of: * A choice of venue clause * Forced distribution to a third party * Forced blanket license to the original developer

Compliance

All legal disputes about the license are settled in

Oslo Oslo ( or ; ) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of 1,064,235 in 2022 ...

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

, but it has never been legally contested.

References

External links

* , version 1.0 {{Qt platform Qt (software) Free and open-source software licenses

History

Adoption

Compliance

See also

References

External links