Software license

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Diagram of software under various licenses according to the FSF and their The Free Software Definition: on the left side "free software", on the right side "proprietary software". On both sides, and therefore mostly orthogonal, "free download" (Freeware).

A software license is a legal instrument governing the use or redistribution of software.

Since the 1970s, software copyright has been recognized in the United States. Despite the copyright being recognized, most companies prefer to sell licenses rather than copies of the software because it enables them to enforce stricter terms on redistribution. Very few purchasers read any part of the license, initially shrink-wrap contracts and now most commonly encountered as clickwrap or browsewrap. The enforceability of this kind of license is a matter of controversy and is limited in some jurisdictions. Service-level agreements are another type of software license where the vendor agrees to provide a level of service to the purchaser, often backed by financial penalties.

Copyleft is a type of license that mandates derivative works to be licensed under the license's terms. Copyleft licenses exist for free and open-source software, but also for commercial applications like the Server Side Public License and others.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The other types of free licenses lack this requirement: for permissive licenses, attribution is typically the only requirement, and public-domain-equivalent licenses have no restrictions. The proliferation of open-source licenses has compounded license compatibility issues, but all share some features: allowing redistribution and derivative works under the same license, unrestricted access to the source code, and nondiscrimination between different uses—in particular, allowing commercial use.

	Free and open			Non-free
	Public domain Template:Sfn and equivalent licenses	Permissive license<ref name=OSIlicenses>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>Template:Sfn !! Copyleft<ref name=OSIlicenses/>Template:Sfn !! Noncommercial licenseTemplate:Sfn !! Proprietary license Template:Sfn !! Trade secret Template:Sfn!! Commercial Copyleft
Description	Waives copyright protection	Grants use rights, including right to relicense (allows proprietization, license compatibility)	Grants use rights, forbids proprietization	Grants rights for noncommercial use only.	Traditional use of copyright; no rights need be granted	No information made public	Grants use rights, but restricts them to certain use cases
Notable software licenses	PD, CC0 Template:Sfn	MIT, Apache, MPL, BSD	GPL, AGPL	JRL Template:Sfn	Proprietary software		SSPL

Software copyrightEdit

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} Template:Computing law The source code (or compiled binaries in the form of object code)Template:Sfn of a computer program is protected by copyright law that vests the owner with the exclusive right to copy the code. The underlying ideas or algorithms are not protected by copyright law, but are often treated as a trade secret and concealed by such methods as non-disclosure agreements.Template:Sfn Software copyright has been recognized since the mid-1970s and is vested in the company that makes the software, not the employees or contractors who wrote it.Template:Sfn

Software licenses and rights granted in context of the copyright according to Mark Webbink.<ref name="redhat2005">{{#invoke:citation/CS1|citation
Rights granted	Public domain and equivalent	Permissive FOSS license (e.g. BSD license)	Copyleft FOSS license (e.g. GPL)	Freeware / Shareware / Freemium	Proprietary license	Trade secret
CitationClass=web }}</ref> Expanded by freeware and sublicensing.
Copyright retained	Template:No	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes
Right to perform	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:No
Right to display	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:Yes	Template:No
Right to copy	Template:Yes	Template:Yes	Template:Yes	Template:Maybe	Template:No	Template:No
Right to modify	Template:Yes	Template:Yes	Template:Yes	Template:No	Template:No	Template:No
Right to distribute	Template:Yes	Template:Maybe	Template:Maybe	Template:Maybe	Template:No	Template:No
Right to sublicense	Template:Yes	Template:Yes	Template:No	Template:No	Template:No	Template:No
Example software	SQLite, ImageJ	Apache web server, ToyBox	Linux kernel, GIMP, OBS	Irfanview, Winamp	Windows, the majority of commercial video games and their DRMs, Spotify, xSplit, TIDAL	Server-side Cloud computing programs and services, forensic applications, and other line-of-business work.

Proprietary software licensesEdit

File:Ohhh, Shockwave (117804940).jpg

A brief, written-out beta test software license issued by Macromedia in 1995

The tendency to license proprietary software, rather than sell it, dates from the time period before the existence, then the scope of software copyright protection was clear. These licenses have continued in use after software copyright was recognized in the courts, and are considered to grant the company extra protection compared to copyright law.Template:Sfn According to United States federal law, a company can restrict the parties to which it sells but it cannot prevent a buyer from reselling the product. Software licensing agreements usually prohibit resale, enabling the company to maximize revenue.Template:Sfn

Traditionally, software was distributed in the form of binary object code that could not be understood or modified by the user,Template:Sfn but could be downloaded and run. The user bought a perpetual license to use a particular version of the software.Template:Sfn Software as service (SaaS) vendors—who have the majority market share in application software Template:As of Template:Sfn—rarely offer perpetual licenses.Template:Sfn SaaS licenses are usually temporary and charged on a pay-per-usage or subscription basis,Template:Sfn although other revenue models such as freemium are also used.Template:Sfn For customers, the advantages of temporary licenses include reduced upfront cost, increased flexibility, and lower overall cost compared to a perpetual license.Template:Sfn In some cases, the steep one-time cost demanded by sellers of traditional software were out of the reach of smaller businesses, but pay-per-use SaaS models makes the software affordable.Template:Sfn

End-user license agreement (EULA)Edit

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Initially, end-user license agreements (EULAs) were printed on either the shrinkwrap packaging encasing the product (see shrink-wrap contract) or a piece of paper. The license often stipulated that a customer agreed if they did not return the product within a specified interval.Template:Sfn More recently, EULAs are most commonly found as clickwrap or browsewrap where the user's clicks or continued browsing are taken as a sign of agreement. As a result of the end of physical constraints, length increased.Template:Sfn Most EULAs have been designed so that it is very difficult to read and understand them, but easy to agree to the licensing terms without reading them.Template:Sfn Template:Sfn Regardless of how easy it is to access, very few consumers read any part of the license agreement.Template:Sfn Template:Sfn Most assume the terms are unobjectionable or barely notice agreeing while installing the software.Template:Sfn Companies take advantage of consumers' inattention to insert provisions into EULAs.Template:Sfn

Proprietary software is usually offered under a restrictive license that bans copying and reuse and often limits the purchaser to using the software on one computer.Template:Sfn Template:Sfn Source code is rarely available. Derivative software works and reverse engineering are usually explicitly prohibited.Template:Sfn Many EULAs allow the vendor to collect information about the user and use it in unrestricted ways.Template:Sfn Some EULAs restrict the ability of users to exercise copyright over derivative work made using the software, such as creative creations in the virtual worlds of video games.Template:Sfn Template:Sfn

Most disclaim any liability for harms caused by the product,Template:Sfn and prevent the purchaser from accessing the court system to seek a remedy.Template:Sfn Furthermore, many EULAs allow the vendor to change the terms at any time and the customer must choose between agreeing or ceasing use of the product, without getting a refund.Template:Sfn It is common for EULAs to allow unilateral termination by the vendor for any number of vague reasons or none at all.Template:Sfn

EULAs, almost always offered on a take-it-or-leave-it basis as a non-negotiable condition for using the software,Template:Sfn are very far from the prototypical contract where both parties fully understand the terms and agree of their own free will.Template:Sfn There has been substantial debate on to what extent the agreements can be considered binding. Before 1996 in the United States, clickwrap or browsewrap licenses were not held to be binding, but since then they often have been.Template:Sfn Template:Sfn Under the New Digital Content Directive effective in the European Union, EULAs are only enforceable to the extent that they do not breach reasonable consumer expectations. The gap between expectations and the content of EULAs is especially wide when it comes to restrictions on copying and transferring ownership of digital content.Template:Sfn Many EULAs contain stipulations that are likely unenforceable depending on the jurisdiction. Software vendors keep these unenforceable provisions in the agreements, perhaps because users rarely resort to the legal system to challenge them.Template:Sfn

Service-level agreement (SLA)Edit

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} Service-level agreements are often used for enterprise software and guarantee a level of service, such as software performance or time to respond to issue raised by the customer. Many stipulate financial penalties if the service falls short of the agreed standard.Template:Sfn SLAs often cover such aspects as availability, reliability, price, and security using quantifiable metrics.Template:Sfn Multi-tier SLAs are common in cloud computing because of the use of different computing services that may be managed by different companies.Template:Sfn SLAs in cloud computing are an area under active research Template:As of.Template:Sfn

Free and open-source software licensesEdit

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Before the open-source movement in the 1980s, almost all software was proprietary and did not disclose its source code.Template:Sfn Open-source licensing is intended to maximize openness and minimize barriers to software use, dissemination, and follow-on innovation.Template:Sfn

Open-source licenses share a number of key characteristics:Template:Sfn

Free redistribution: Anyone can redistribute the software, for free or for cost, without the permission of or payment to the copyright holder.Template:Sfn
Unrestricted, public access to the source code Template:Sfn—what the term open source refers toTemplate:Sfn
Users may modify the software and release derivative works, either under the same terms as the free software or, in some cases, under a different license.Template:Sfn
Nondiscrimination between different uses,Template:Sfn including commercial use.Template:Sfn Template:Sfn

The Open Source Initiative vets and approves new open-source licenses that comply with its Open Source Definition.Template:Sfn

Types of open-source licensesEdit

File:Open-source-license-chart.svg

The most popular open source licenses as of 2022 are the Apache License (permissive), the MIT License (permissive), and the GPL (copyleft).

If software is in the public domain, the owner's copyright has been extinguished and anyone may use the work with no copyright restrictions.Template:Sfn
Non-restrictive licenses allow free reuse of the work without restrictions on the licensing of derivative works.Template:Sfn Many of them require attribution of the original creators.Template:Sfn The first open-source license was a non-restrictive license intended to facilitate scientific collaboration: the Berkeley Software Distribution (BSD), named after the University of California, Berkeley in 1978.Template:Sfn
Copyleft licenses (also known as "share-alike"),Template:Sfn require source code to be distributed with software and require the source code be made available under a similar license.Template:Sfn Template:Sfn Copyleft represents the farthest that reuse can be restricted while still being considered free software.Template:Sfn Strong copyleft licenses, such as the GNU General Public License (GPL), allow for no reuse in proprietary software, while weak copyleft, such as the related GNU Lesser General Public License (LGPL), do allow reuse in some circumstances.Template:Sfn Copyleft licenses are perceived by developers as a way of ensuring that their contributions do not create unfair advantages for others.Template:Sfn Template:Sfn Another motivation for choosing copyleft is to promote open source through its requirements for derivative works:Template:Sfn Stallman states that "the central idea of copyleft is to use copyright law, but flip it over to serve the opposite of its usual purpose: instead of a means of privatizing software, [copyright] becomes a means of keeping software free."Template:Sfn

Outside of software, noncommercial-only Creative Commons licenses have become popular among some artists who wish to prevent others from profiting excessively from their work.Template:Sfn However, software that is made available for noncommercial use only is not considered open source.Template:Sfn Sun Microsystems' noncommercial-only Java Research License was rejected by the open-source community, and in 2006 the company released most of Java under the GPL.Template:Sfn

CompatibilityEdit

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File:GPL-Compatible.svg

Compatibility chart for some open-source software licenses

Since 1989,Template:Sfn a variety of open-source licenses for software have been created.Template:Sfn Choosing an open-source software license has grown increasingly difficult due to the proliferation of licenses,Template:Sfn Template:Sfn many of which are only trivially distinct.Template:Sfn Many licenses are incompatible with each other, hampering the goals of the free software movement.Template:Sfn Translation issues, ambiguity in licensing terms, and incompatibility of some licenses with the law in certain jurisdictions compounds the problem.Template:Sfn

Although downloading an open-source module is quick and easy, complying with the licensing terms can be more difficult.Template:Sfn The amount of software dependencies means that engineers working on complex projects must often rely on software license management software in order to help them achieve compliance with the licensing terms of open-source components.Template:Sfn Many open-source software files do not unambiguously state the license, increasing the difficulties of compliance.Template:Sfn When combining code bases, the original licenses can be maintained for separate components, and the larger work released under a compatible license.Template:Sfn This compatibility is often one-way. Public domain content can be used anywhere as there is no copyright claim, but code acquired under almost any set of terms cannot be waved to the public domain. Permissive licenses can be used within copyleft works, but copyleft material cannot be released under a permissive license. Some weak copyleft licenses can be used under the GPL and are said to be GPL-compatible. GPL software can only be used under the GPL or AGPL.Template:Sfn

EnforceabilityEdit

Template:Further Free and open-source software licenses have been successfully enforced in civil court since the mid-2000s.Template:Sfn Courts have found that distributing software indicates acceptance of the license's terms.Template:Sfn However, developers typically achieve compliance without lawsuits. Social pressures, such as the potential for community backlash, are often sufficient.Template:Sfn Cease and desist letters are a common method to bring companies back into compliance, especially in Germany.Template:Sfn

A long-debated subject within the FOSS community is whether open-source licenses are "bare licenses" or contracts.Template:Sfn A bare license is a set of conditions under which actions otherwise restricted by intellectual property laws are permitted.Template:Sfn Under the bare license interpretation, advocated by the Free Software Foundation (FSF), a case is brought to court by the copyright holder as copyright infringement.Template:Sfn Under the contract interpretation, a case can be brought to court by an involved party as a breach of contract.Template:Sfn United States and French courts have tried cases under both interpretations.Template:Sfn

ValueEdit

More than 90 percent of companies use open-source software as a component of their proprietary software.Template:Sfn The decision to use open-source software, or even engage with open-source projects to improve existing open-source software, is typically a pragmatic business decision.Template:Sfn Template:Sfn When proprietary software is in direct competition with an open-source alternative, research has found conflicting results on the effect of the competition on the proprietary product's price and quality.Template:Sfn

For decades, some companies have made servicing of an open-source software product for enterprise users as their business model. These companies control an open-source software product, and instead of charging for licensing or use, charge for improvements, integration, and other servicing.Template:Sfn Software as a service (SaaS) products based on open-source components are increasingly common.Template:Sfn

Open-source software is preferred for scientific applications, because it increases transparency and aids in the validation and acceptance of scientific results.Template:Sfn

ReferencesEdit

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SourcesEdit

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External linksEdit

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