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MIT License

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MIT License
PublisherMassachusetts Institute of Technology
SPDXidentifierMIT
(see list for more)[1]
Debian FSG compatibleYes[2]
FSFapprovedYes[3][4]
OSIapprovedYes[5]
GPL compatibleYes[3][4]
CopyleftNo[3][4]
Linking from code with a different licenceYes

TheMIT Licenseis apermissive software licenseoriginating at theMassachusetts Institute of Technology(MIT)[6]in the late 1980s.[7]As a permissive license, it puts very few restrictions on reuse and therefore has highlicense compatibility.[8][9]

Unlikecopyleftsoftware licenses, the MIT License also permits reuse withinproprietary 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.[9][10]In 2015, the MIT License was the most popular software license onGitHub.[11]

Notable projects that use the MIT License include theX Window System,Ruby on Rails,Node.js,Lua,jQuery,.NET,Angular,andReact.

License terms

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The MIT License has the identifierMITin theSPDXLicense List.[12][13]It is also known as the "Expat License".[3]It has the following terms:[14] 

Copyright (c) <year> <copyright holders>

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 Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Variations

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X11 License

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TheX11 License,also known as theMIT/X Consortium License,is a variation on the MIT license, most known for its usage by theX Consortium.[15]It has the identifierX11in theSPDXLicense List.[16][4]

It differs from the MIT License mainly by an additional clause restricting use of the copyright holders' name for advertisement.

It has the following terms:[17] 

Copyright (C) <date> <copyright holders>

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 Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of <copyright holders> shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from <copyright holders>.

MIT No Attribution License

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MIT No Attribution License
AuthorRoman Mamedov,Amazon Web Services
Published28 March 2018
SPDXidentifierMIT-0
Debian FSG compatiblen/a
FSFapprovedn/a
OSIapprovedYes[18]
GPL compatibleYes
CopyleftNo
Linking from code with a different licenceYes
Websitehttps://github /aws/mit-0

The MIT No Attribution License, a variation of the MIT License, has the identifierMIT-0in theSPDXLicense List.[19]A request for legacy approval to theOpen Source Initiativewas filed on May 15, 2020,[20]which led to a formal approval on August 5, 2020.[18]By doing so, it forms apublic-domain-equivalent license,the same way asBSD Zero Clause.[citation needed]It has the following terms: 

MIT No Attribution

Copyright <YEAR> <COPYRIGHT HOLDER>

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 Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Other variations

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TheSPDXLicense List contains extra MIT license variations. Examples include:[1]

  • MIT-advertising,a variation with an additional advertising clause.

There is also the Anti-Capitalist Software License (ACSL),[21]built off of the MIT license. It is not Open Source, since it limits the permissions granted to individuals and organizations that do not operate under capitalist structures, like non-profits and cooperatives.

Ambiguity and variants

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The name "MIT License" is potentially ambiguous. The Massachusetts Institute of Technology has used many licenses for software since its creation; for example, MIT offers four licensing options for theFFTW[22]C source code library, one of which is theGPL v2.0and the other three of which are notopen-source.The term "MIT License" has also been used to refer to theExpat License(used for the XML parsing libraryExpat) and to theX11 License(also called "MIT/X Consortium License";used forX Window Systemby theMIT X Consortium).[3]Furthermore, the "MIT License" as published by theOpen Source Initiativeis the same as the Expat License.[13]Due to this differing use of terms, some prefer to avoid the name "MIT License".[7]TheFree Software Foundationargues that the term is misleading and ambiguous, and recommends against its use.[3]

The X Consortium was dissolved late in 1996, and its assets transferred toThe Open Group,[23]which released X11R6 initially under the same license. The X11 License[4]and the X11R6 "MIT License" chosen forncursesby the Free Software Foundation[24]both include the following clause, absent in the Expat License:[3]

Except as contained in this notice, the name(s) of the above copyright holders shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization.

As of 2020, the successor to the X Window System is theX.Org Server,which is licensed under what is effectively the common MIT license, according to the X.org licensing page:[25]

The X.Org Foundation has chosen the following format of the MIT License as the preferred format for code included in the X Window System distribution. This is a slight variant of the common MIT license form published by the Open Source Initiative

The "slight variant" is the addition of the phrase "(including the next paragraph)" to the second paragraph of the license text, resulting in: "The above copyright notice and this permission notice (including the next paragraph) shall be included in all copies or substantial portions of the Software." This inclusion clarifies that the liability paragraph must also be included for the conditions of the license to be met.[25]

The license-management features at popular source code repositoryGitHub,as well as its "Choose a License" service, do not differentiate between MIT/Expat license variants. The text of the Expat variant is presented as simply the "MIT License" (represented by themetadatatagmit).[26][27]

Comparison to other licenses

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BSD

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The originalBSD licensealso includes a clause requiring all advertising of the software to display a notice crediting its authors. This "advertising clause" (since disavowed by UC Berkeley[28]) is present in the modified MIT License used byXFree86.

TheUniversity of Illinois/NCSA Open Source Licensecombines text from both the MIT and BSD licenses; the license grant and disclaimer are taken from the MIT License.

TheISC licensecontains similarities to both the MIT and simplified BSD licenses, the biggest difference being that language deemed unnecessary by theBerne Conventionis omitted.[29][30]

GNU General Public License

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The GPL is explicit about thepatentrights an owner grants when the code orderivative workis distributed,[31]the MIT license does not discuss patents. Moreover, the GPL license impacts derivative works, but the MIT license does not.

Relation to patents

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Like the BSD license, the MIT license does not include an express patent license although some commentators[32][33]state that the grant of rights covers all potential restrictions including patents. Both the BSD and the MIT licenses were drafted before the patentability of software was generally recognized under US law.[34]TheApache Licenseversion 2.0[3]is a similarly permissive license that includes an explicit contributor's patent license. Of specific relevance to US jurisdictions, the MIT license uses the terms "sell" and "use" that are also used in defining the rights of a patent holder inTitle 35 of the United States Codesection 154. This has been construed by some commentators[35][36]as an unconventional but implicit license in the US to use any underlying patents.

Origins

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One of the originators of the MIT license, computer scientistJerry Saltzer,has published his recollections of its early development, along with documentary evidence.[37][7]

Reception

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As of 2020,according to WhiteSource Software[38]the MIT license was used in 27% of four million open source packages. As of 2015,according to Black Duck Software[39][better source needed]and a 2015 blog[11]fromGitHub,the MIT license was the most popularopen-source license,with theGNU GPLv2coming second in their sample of repositories.

See also

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References

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  1. ^ab"SPDX License List".spdx.org.SPDX Working Group.
  2. ^"License information".TheDebian Project.Software in the Public Interest(published July 12, 2017). 1997–2017.Archivedfrom the original on July 20, 2017.RetrievedJuly 20,2017.This page presents the opinion of some debian-legal contributors on how certain licenses follow the Debian Free Software Guidelines (DFSG).... Licenses currently found in Debian main include:... Expat/MIT-style licenses...
  3. ^abcdefgh"Various Licenses and Comments about Them".TheGNU Project.Free Software Foundation(published April 4, 2017). 2014–2017. Expat License.Archivedfrom the original on July 20, 2017.RetrievedJuly 20,2017.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.
  4. ^abcde"Various Licenses and Comments about Them".TheGNU Project.Free Software Foundation(published April 4, 2017). 2014–2017. X11 License.Archivedfrom the original on July 20, 2017.RetrievedJuly 20,2017.This is a lax permissive non-copyleft free software license, compatible with the GNU GPL.... This license is sometimes called the MIT license, but that term is misleading, since MIT has used many licenses for software.
  5. ^"Licenses by Name".Open Source Initiative.n.d.Archivedfrom the original on July 20, 2017.RetrievedJuly 20,2017.The following licenses have been approved by the OSI.... MIT License (MIT)...
  6. ^Rosen, Lawrence E. (2005).Open Source Licensing: Software Freedom and Intellectual Property Law.Upper Saddle River, NJ:Prentice Hall PTR.ISBN0-13-148787-6.OCLC56012651.
  7. ^abcHaff, Gordon."The mysterious history of the MIT License".opensource.RetrievedJuly 30,2019.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.
  8. ^Hanwell, Marcus D. (January 28, 2014)."Should I use a permissive license? Copyleft? Or something in the middle?".opensource.RetrievedMay 30,2015.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.
  9. ^ab"Licence Compatibility and Interoperability".Open-Source Software - Develop, share, and reuse open source software for public administrations.Joinup. Archived fromthe originalon June 17, 2015.RetrievedMay 30,2015.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" ).
  10. ^"Paid software includes MIT licensed library, does that put my app under MIT too?".Software Engineering Stack Exchange.RetrievedJuly 21,2021.
  11. ^abBalter, Ben (March 9, 2015)."Open source license usage on GitHub".The GitHub Blog.RetrievedNovember 21,2015.1 MIT 44.69%, 2 Other 15.68%
  12. ^"MIT License".SPDX.Archivedfrom the original on May 8, 2024.
  13. ^ab"The MIT License".Open Source Initiative.RetrievedDecember 5,2010.
  14. ^"MIT License Explained in Plain English - TLDRLegal".tldrlegal.RetrievedJuly 7,2021.
  15. ^"3.3. X Consortium",3. X/MIT Licenses,The XFree86 Project, March 2004
  16. ^"X11 License".spdx.org.SPDX Working Group.
  17. ^"X11 License Explained in Plain English - TLDRLegal".tldrlegal.Archived fromthe originalon March 3, 2021.RetrievedMarch 26,2021.
  18. ^abChestek, Pamela (August 5, 2020)."[License-review] Request for Legacy Approval of MIT No Attribution License".
  19. ^"MIT No Attribution".spdx.org.SPDX Working Group.
  20. ^Langel, Tobie (May 15, 2020)."[License-review] Request for Legacy Approval of MIT No Attribution License".
  21. ^"The Anti-Capitalist Software License".anticapitalist.software.RetrievedMay 8,2024.
  22. ^"FFTW - Fastest Fourier Transform in the West".Massachusetts Institute of Technology.RetrievedJuly 17,2020.
  23. ^Dickey, Thomas E."Copyrights/comments".RetrievedOctober 6,2020.
  24. ^Dickey, Thomas E."NCURSES — Frequently Asked Questions (FAQ)".
  25. ^ab"Licenses".X.Org Foundation.
  26. ^"Licensing a repository".GitHub Docs.
  27. ^"MIT License".ChooseALicense.GitHub.September 5, 2022.
  28. ^"To All Licensees, Distributors of Any Version of BSD".University of California, Berkeley. July 22, 1999.RetrievedNovember 15,2006.
  29. ^"Copyright Policy".OpenBSD.RetrievedJune 6,2016.The ISC copyright is functionally equivalent to a two-term BSD copyright with language removed that is made unnecessary by the Berne convention.
  30. ^de Raadt, Theo(March 21, 2008)."Re: BSD Documentation License?".openbsd-misc(Mailing list).
  31. ^"Patents and GPLv3 - FSFE".FSFE - Free Software Foundation Europe.RetrievedDecember 1,2020.
  32. ^"Why so little love for the patent grant in the MIT License?".January 23, 2021. Archived fromthe originalon January 23, 2021.RetrievedJanuary 23,2021.
  33. ^"Free and open source software and your patents".May 3, 2020. Archived fromthe originalon May 3, 2020.RetrievedMay 3,2020.
  34. ^Stern and Allen, Open Source Licensing, p. 495 in Understanding the Intellectual Property License 2013 (Practicing Law Institute 2013)
  35. ^"The MIT License, Line by Line".May 3, 2020. Archived fromthe originalon May 3, 2020.RetrievedMay 3,2020.
  36. ^ Christian H. Nadan (2009),"Closing the Loophole: Open Source Licensing & the Implied Patent License",The Computer & Internet Lawyer,26(8), Aspen Law & Business,By using patent terms like "deal in", "use", and "sell", the MIT license grant is more likely to be deemed to include express patent rights than the BSD license.
  37. ^ Saltzer, Jerome H (November 18, 2020)."The origin of the" MIT license "".IEEE Annals of the History of Computing.42(4): 94–98.doi:10.1109/MAHC.2020.3020234.ISSN1934-1547.Open access icon
  38. ^"Open Source Licenses in 2020: Trends and Predictions".May 3, 2020. Archived fromthe originalon May 3, 2020.RetrievedMay 3,2020.
  39. ^"Top 20 licenses".Black Duck Software. November 19, 2015. Archived fromthe originalon September 4, 2013.RetrievedNovember 19,2015.1. MIT license 24%, 2. GNU General Public License (GPL) 2.0 23%

Further reading

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