Editing MIT License (section)

{{short description|Permissive free software license}}
{{Use American English|date=March 2021}}
{{Use mdy dates|date=March 2021}}
{{Infobox software license
| name = MIT License
| image = [[File:MIT logo.svg|140px]]
| author = <!-- An author is always a person. Something more clever than "Massachusetts Institute of Technology", please! -->
| copyright = [[Massachusetts Institute of Technology]]
| spdx = MIT<br />(see list for more)<ref name="SPDX License List" />
| OSI approved = Yes<ref name="osi-licenses">{{Cite web |url=https://opensource.org/licenses/alphabetical |title=Licenses by Name |date=n.d. |website=[[Open Source Initiative]] |access-date=2017-07-20 |archive-url=https://web.archive.org/web/20170720141629/https://opensource.org/licenses/alphabetical |url-status=live |archive-date=2017-07-20 |quote=The following licenses have been approved by the OSI. ...&nbsp;MIT License (MIT)&nbsp;...}}</ref>
| Debian approved = Yes<ref name="dfsg-licenses">{{Cite web |url=https://www.debian.org/legal/licenses/ |title=License information |date=1997–2017 |publication-date=2017-07-12 |website=The [[Debian Project]] |publisher=[[Software in the Public Interest]] |access-date=2017-07-20 |archive-url=https://web.archive.org/web/20170720142826/https://www.debian.org/legal/licenses/ |url-status=live |archive-date=2017-07-20 |quote=This page presents the opinion of some debian-legal contributors on how certain licenses follow the Debian Free Software Guidelines (DFSG).&nbsp;... Licenses currently found in Debian main include: ...&nbsp;Expat/MIT-style licenses&nbsp;...}}</ref>
| Free Software = Yes<ref name="gnu-license-list-expat">{{Cite web |url=https://www.gnu.org/licenses/license-list.en.html#Expat |title=Various Licenses and Comments about Them |date=2014–2017 |publication-date=2017-04-04 |website=The [[GNU Project]] |publisher=[[Free Software Foundation]] |at=Expat License |access-date=2017-07-20 |archive-url=https://web.archive.org/web/20170720140022/https://www.gnu.org/licenses/license-list.en.html |url-status=live |archive-date=2017-07-20 |quote=This is a lax, permissive non-copyleft free software license, compatible with the GNU GPL. It is sometimes ambiguously referred to as the MIT License.}}</ref><ref name="gnu-license-list-x11">{{Cite web |url=https://www.gnu.org/licenses/license-list.en.html#X11License |title=Various Licenses and Comments about Them |date=2014–2017 |publication-date=2017-04-04 |website=The [[GNU Project]] |publisher=[[Free Software Foundation]] |at=X11 License |access-date=2017-07-20 |archive-url=https://web.archive.org/web/20170720140022/https://www.gnu.org/licenses/license-list.en.html |url-status=live |archive-date=2017-07-20 |quote=This is a lax permissive non-copyleft free software license, compatible with the GNU GPL.&nbsp;... This license is sometimes called the MIT license, but that term is misleading, since MIT has used many licenses for software.}}</ref>
| GPL compatible = Yes<ref name="gnu-license-list-expat"/><ref name="gnu-license-list-x11"/>
| copyleft = No<ref name="gnu-license-list-expat"/><ref name="gnu-license-list-x11"/>
| linking = Yes
}}
The '''MIT License''' is a [[permissive software license]] originating at the [[Massachusetts Institute of Technology]] (MIT)<ref>{{Cite book |last=Rosen |first=Lawrence E. |url=https://www.worldcat.org/oclc/56012651 |title=Open Source Licensing: Software Freedom and Intellectual Property Law |publisher=[[Prentice Hall PTR]] |year=2005 |isbn=0-13-148787-6 |location=Upper Saddle River, NJ |oclc=56012651}}</ref> in the late 1980s.<ref name="history">{{cite web |last=Haff |first=Gordon |title=The mysterious history of the MIT License |url=https://opensource.com/article/19/4/history-mit-license |access-date=2019-07-30 |work=opensource.com |quote=The date? The best single answer is probably 1987. But the complete story is more complicated and even a little mysterious. [...] Precursors from 1985. The X Consortium or X11 License variant from 1987. Or the Expat License from 1998 or 1999.}}</ref> As a permissive license, it puts very few restrictions on reuse and therefore has high [[license compatibility]].<ref name="opensoucecomp">{{cite web|url=http://opensource.com/business/14/1/what-license-should-i-use-open-source-project |quote=Permissive licensing simplifies things One reason the business world, and more and more developers [...], favor permissive licenses is in the simplicity of reuse. The license usually only pertains to the source code that is licensed and makes no attempt to infer any conditions upon any other component, and because of this there is no need to define what constitutes a derived work. I have also never seen a license compatibility chart for permissive licenses; it seems that they are all compatible.|title=Should I use a permissive license? Copyleft? Or something in the middle? |date=2014-01-28 |access-date=2015-05-30 |first=Marcus D. |last=Hanwell |publisher=opensource.com}}</ref><ref name="comaptible">{{cite web |url=https://joinup.ec.europa.eu/software/page/licence_compatibility_and_interoperability |work=Open-Source Software  |title=Licence Compatibility and Interoperability |publisher=Joinup |quote=The licences for distributing free or open source software (FOSS) are divided in two families: permissive and copyleft. Permissive licences (BSD, MIT, X11, Apache, Zope) are generally compatible and interoperable with most other licences, tolerating to merge, combine or improve the covered code and to re-distribute it under many licences (including non-free or "proprietary"). |access-date=2015-05-30 |url-status=dead |archive-url=https://web.archive.org/web/20150617130550/https://joinup.ec.europa.eu/software/page/licence_compatibility_and_interoperability |archive-date=2015-06-17 }}</ref>

Unlike [[copyleft]] software licenses, the MIT License also permits reuse within [[proprietary software]], provided that all copies of the software or its substantial portions include a copy of the terms of the MIT License and also a copyright notice.<ref name="comaptible"/><ref>{{cite web |url=https://softwareengineering.stackexchange.com/questions/264700/paid-software-includes-mit-licensed-library-does-that-put-my-app-under-mit-too |title=Paid software includes MIT licensed library, does that put my app under MIT too? |website=Software Engineering Stack Exchange |access-date=21 July 2021 }}</ref> In 2015, the MIT License was the most popular software license on [[GitHub]],<ref name="github2015" /> and was still the most popular in 2025.<ref>{{Cite web |title=GitHub Innovation Graph |url=https://innovationgraph.github.com/global-metrics/licenses |access-date=2025-01-08 |website=innovationgraph.github.com |language=en}}</ref>

Notable projects that use the MIT License include the [[X Window System]], [[Ruby on Rails]], [[Node.js]], [[Lua (programming language)|Lua]], [[jQuery]], [[.NET]], [[Angular (web framework)|Angular]], and [[React (JavaScript library)|React]].