Public-domain software

Public-domain software is software that has been placed in the public domain, in other words, software for which there is absolutely no ownership such as copyright, trademark, or patent. Software in the public domain can be modified, distributed, or sold even without any attribution by anyone; this is unlike the common case of software under exclusive copyright, where licenses grant limited usage rights.

The Creative Commons Public Domain Mark indicates works that are in the public domain

Under the Berne Convention, which most countries have signed, an author automatically obtains the exclusive copyright to anything they have written, and local law may similarly grant copyright, patent, or trademark rights by default. The Convention also covers programs, and they are therefore automatically subject to copyright. If a program is to be placed in the public domain, the author must explicitly disclaim the copyright and other rights on it in some way, e.g. by a waiver statement.[1] In some jurisdictions, some rights (in particular moral rights) cannot be disclaimed: for instance, civil tradition-based German law's "Urheberrecht" differs from Anglo-Saxon common law tradition's "copyright" concept.



Early academic public-domain software ecosystem


From the software culture of the 1950s to 1990s, public-domain (or PD) software were popular as original academic phenomena. This kind of freely distributed and shared "free software" combined the present-day classes of freeware, shareware, and free and open-source software, and was created in academia, by hobbyists, and hackers.[2] As software was often written in an interpreted language such as BASIC, the source code was needed and therefore distributed to run the software. PD software was also shared and distributed as printed source code (type-in programs) in computer magazines (like Creative Computing, SoftSide, Compute!, Byte, etc.) and books, like the bestseller BASIC Computer Games.[3] Earlier on, closed-source software was uncommon until the mid-1970s to 1980s.[4][5][6]

Before 1974, when the US Commission on New Technological Uses of Copyrighted Works (CONTU) decided that "computer programs, to the extent that they embody an author's original creation, are proper subject matter of copyright",[7][8] software was not copyrightable and therefore always in the public domain. This legislation, plus court decisions such as Apple v. Franklin in 1983 for object code, clarified that the Copyright Act gave computer programs the copyright status of literary works.

In the 1980s, a common way to share public-domain software[verification needed] was by receiving them through a local user group or a company like PC-SIG of Sunnyvale, California, which maintained a mail-order catalog of more than 300 disks with an average price of US$6.[9] Public-domain software with source code was also shared on BBS networks. Public-domain software was commercialized sometimes by a donationware model, asking the users for a financial donation to be sent by mail.[10]

The public-domain "free sharing" and donationware commercialization models evolved in the following years to the (non-voluntary) shareware model,[11][12] and software free of charge, called freeware.[13] Additionally, due to other changes in the computer industry, the sharing of source code became less common.[6]

With the Berne Convention Implementation Act of 1988 (and the earlier Copyright Act of 1976), the legal basis for public-domain software changed drastically. Before the act, releasing software without a copyright notice was enough to dedicate it to the public domain. With the new act, software was by default copyright-protected and needed an explicit waiver statement or license from the author.[14][15]

Reference implementations of algorithms, often cryptographic meant or applied for standardization are still often released into the public domain; examples include CERN httpd[16] in 1993 and Serpent cipher in 1999. The Openwall Project maintains a list of several algorithms and their source code in the public domain.[17]

Free and open-source software as successor


As a response of the academic software ecosystem to the change in the copyright system in the late 1980s, permissive license texts were developed, like the BSD license and its derivatives. Permissive-licensed software, which is a kind of free and open-source software, shares most characteristics of earlier public-domain software but stands on the legal basis of copyright law.

In the 1980s Richard Stallman, who for long worked in an academic environment of "public-domain"-like software sharing, noticed the emergence of proprietary software and the decline of the public-domain software ecosystem. In an effort to preserve this ecosystem he created a software license, the GPL, which encodes the public-domain rights and enforces them irrevocably on software. Paradoxically, his copyleft approach relies on the enforceability of the copyright to be effective. Copyleft free software, therefore, shares many properties with public-domain software, but does not allow relicensing or sublicensing. Unlike real public-domain software or permissive-licensed software, Stallman's copyleft license tries to enforce the free shareability of software also for the future by not allowing license changes.

To refer to free software (which is under a free software license) or to software distributed and usable free of charge (freeware) as "public-domain" is therefore incorrect. While public domain gives up the author's exclusive rights (e.g. copyright), in free software the author's copyright is still retained and used, for instance, to enforce copyleft or to hand out permissive-licensed software. Licensed software is in general not in the public domain.[18] Another distinct difference is that an executable program may be in the public domain even if its source code is not made available (making the program not feasibly modifiable), while free software always has the source code available.

Post-copyright public domain


With the 2000s and the emergence of peer-to-peer sharing networks and sharing in web development, a new copyright-critical generation of developers made the "license-free" public-domain software model visible again, also criticizing the FOSS license ecosystem ("Post Open Source") as stabilizing part of the copyright system.[19][20][21][22] New non-FOSS licenses and waiver texts were developed, notably the Creative Commons "CC0" (2009) and the "Unlicense" (2010), and there was a noticeable rise in the popularity of permissive software licenses. Also, the growing problem of orphaned software and digital obsolescence of software raised awareness of the relevance of again passing software into the public domain for better preservation of the digital heritage, unrestricted by copyright and digital rights management.[23][24][25][26]

Around 2004, there was debate on whether public-domain software could be considered part of the FOSS ecosystem, as argued by lawyer Lawrence Rosen in the essay "Why the public domain isn't a license",[27] a position that faced opposition by Daniel J. Bernstein and others.[28] In 2012, the status was finally resolved when Rosen changed his mind and accepted the CC0 as an open-source license, while admitting that, contrary to previous claims, copyright could be waived, as backed by a Ninth Circuit decision.[29]

Passing of software into the public domain


Before the Berne Convention Implementation Act of 1988 (and the earlier Copyright Act of 1976, which went into effect in 1978) works could be easily given into the public domain by releasing them without an explicit copyright notice and no copyright registration. After 1988, all works were by default copyright protected and needed to be actively given into the public domain by a waiver statement.[14][15]


Copyrighted works, like software, are meant to pass into the public domain after the copyright term, losing their copyright privilege. Due to the decades-long copyright protection granted by the Berne Convention, no software has ever passed into the public domain by leaving copyright terms. The question of how quickly works should pass into the public domain has been a matter of scientific[30][31][32] and public debates, as well as for software like video games.[24][25][26]

Public-domain-like licenses and waivers

WTFPL license logo, a public-domain-like license
CC0 license logo, a copyright waiver , and public-domain-like license[33]

While real public domain makes software licenses unnecessary, as no owner/author is required to grant permission ("Permission culture"), there are licenses that grant public-domain-like rights. There is no universally agreed-upon license, but there are multiple licenses that aim to release source code into the public domain.

In 2000 the WTFPL was released as a public-domain-like license/waiver/anti-copyright notice.[34] In 2009 the Creative Commons released the CC0, which was created for compatibility with various law domains (e.g. civil law of continental Europe) where dedicating to public domain is problematic. This is achieved by a public domain waiver statement and a fallback all-permissive license, in case the waiver is not possible.[35][36] The Unlicense, published around 2010, has a focus on an anti-copyright message. The Unlicense offers a public domain waiver text with a fallback public-domain-like license inspired by permissive licenses but without attribution clause.[37][38] In 2015, GitHub reported that of the approximately 5.1 million licensed projects it hosted, almost 2% used the Unlicense.[39] Another popular option is the Zero Clause BSD license, released in 2006 and aimed at software.[40]

As result, such licensed public-domain software has all the four freedoms but is not hampered by the complexities of attribution (restriction of permissive licensed software) or license compatibility (issue with copyleft licensed software).

Public-domain software


See also Category:Public-domain software with source code, Category:Public-domain software

Classical PD software (pre-1988)


Public domain software in the early computer age was, for instance, shared as type-in programs in computer magazines and books like BASIC Computer Games. Explicit PD waiver statements or license files were at that time unusual. Publicly available software without a copyright notice was assumed to be, and shared as, public-domain software.

Notable general PD software from that time include:

Video games are among the earliest examples of shared PD software, which are still notable today:

Many PD software authors kept the practices of public-domain release without having a waiver text, not knowing or caring for the changed copyright law, thus creating a legal problem. On the other hand, magazines started in the mid-1980s to claim copyright even for type-in programs that were previously seen as PD.[45][46] Only slowly did PD software authors start to include explicit relinquishment or license statement texts.

Examples of modern PD software (post 1988)


These examples of modern PD software (after the Berne Convention Implementation Act of 1988) are either under proper public domain (e.g. created by a US governmental organization), under a proper public domain like license (for instance CC0), or accompanied by a clear waiver statement from the author. Whilst not as widespread as in the pre-2000s, PD software still exists nowadays. For example, SourceForge listed 334 hosted PD projects in 2016,[47] and GitHub 102,000 under the Unlicense alone in 2015.[39] In 2016, an analysis of the Fedora Project's packages revealed PD was the seventh most popular "license".[48]

The award-winning video game developer Jason Rohrer releases his works into the PD, as do several cryptographers, such as Daniel J. Bernstein, Bruce Schneier and Douglas Crockford,[49] with reference implementations of cryptographic algorithms.

See also



  1. ^ Open Source: Technology and Policy by Fadi P. Deek, James A. M. McHugh "Public domain", page 227 (2008).
  2. ^ Shea, Tom (1983-06-23). "Free software - Free software is a junkyard of software spare parts". InfoWorld. Retrieved 2016-02-10. In contrast to commercial software is a large and growing body of free software that exists in the public domain. Public-domain software is written by microcomputer hobbyists (also known as "hackers") many of whom are professional programmers in their work life.
  3. ^ Ahl, David. "David H. Ahl biography from Who's Who in America". Retrieved 2009-11-23.
  4. ^ Object code only: is IBM playing fair? IBM's OCO policy protects its own assets but may threaten customers investment on Computerworld - 8 Febr. 1988
  5. ^ Firm sidestep IBM policy by banning software changes on Computerworld (18 March 1985)
  6. ^ a b Gallant, John (1985-03-18). "IBM policy draws fire – Users say source code rules hamper change". Computerworld. Retrieved 2015-12-27. While IBM's policy of withholding source code for selected software products has already marked its second anniversary, users are only now beginning to cope with the impact of that decision. But whether or not the advent of object-code-only products has affected their day-to-day DP operations, some users remain angry about IBM's decision. Announced in February 1983, IBM's object-code-only policy has been applied to a growing list of Big Blue system software products
  7. ^ Apple Computer, Inc. v. Franklin Computer Corporation Puts the Byte Back into Copyright Protection for Computer Programs in Golden Gate University Law Review Volume 14, Issue 2, Article 3 by Jan L. Nussbaum (January 1984)
  8. ^ Lemley, Menell, Merges and Samuelson. Software and Internet Law, p. 34.
  9. ^ Kristina B. Sullivan (1986-01-14). "Hackers Create Public-Domain Software for the Sheer Joy of It". PC Week. Vol. 3, no. 2. pp. 121–122.
  10. ^ April 1987: Ballerburg - Zwei Spieler, zwei Burgen und ein Berg dazwischen... on "Ich habe das Programm als Public Domain veröffentlicht (die Unterscheidung in Freeware, Shareware usw. gab es damals nicht), mit der Bitte um eine 20 DM Spende. Dafür gab es dann die erweitere Version und den Quellcode." (in German).
  11. ^ "Bob Wallace Timeline". Erowid. Jan 12, 2004. Retrieved March 7, 2013.
  12. ^ Article about Jim "Button" Knopf, from Dr. Dobb's Journal.
  13. ^ the-history-of-shareware-psl on
  14. ^ a b publicdomain on
  15. ^ a b Copyright Notice, U.S. Copyright Office Circular 3, 2008.
  16. ^ The birth of the web Licensing the web on (2014).
  17. ^ Source code snippets and frameworks placed in the public domain on
  18. ^ Shankland, Stephen (February 28, 2008). "Is public domain software open-source?". Retrieved 2016-02-03. There's no doubt that open-source software and that in the public domain are similar. But even experts differ about just how closely linked they are.
  19. ^ The Surprising History of Copyright and The Promise of a Post-Copyright World by Karl Fogel (2006).
  20. ^ Younger developers reject licensing, risk chance for reform on by Luis Villa (on 12 Feb 2013).
  21. ^ Pushing back against licensing and the permission culture Luis Villa (January 28, 2013).
  22. ^ Post open source software, licensing and GitHub on by Richard Fontana (on 13 Aug 2013).
  23. ^ Charlesworth, Andrew (5 November 2002). "The CAMiLEON Project: Legal issues arising from the work aiming to preserve elements of the interactive multimedia work entitled "The BBC Domesday Project"". Kingston upon Hull: Information Law and Technology Unit, University of Hull. Archived from the original (Microsoft Word) on 6 February 2011. Retrieved 23 March 2011.
  24. ^ a b Walker, John (2014-01-29). "GOG's Time Machine Sale Lets You CONTROL TIME ITSELF". Rock, Paper, Shotgun. Retrieved 2016-01-30. As someone who desperately pines for the PD model that drove creativity before the copyright industry malevolently took over the planet, it saddens my heart that a game two decades old isn't released into the world.
  25. ^ a b Walker, John (2014-02-03). "Editorial: Why Games Should Enter The Public Domain". Rock, Paper, Shotgun. Retrieved 2016-01-30. games more than a couple of decades old aren't entering the public domain. Twenty years was a fairly arbitrary number, one that seems to make sense in the context of games' lives, but it could be twenty-five, thirty.
  26. ^ a b Rouner, Jef (April 28, 2015). "U.S. Copyright Office to Explore Making Some Video Games Public Domain". Houston Press. Retrieved 2016-02-03.
  27. ^ Lawrence Rosen (2004-05-25). "Why the public domain isn't a license". Retrieved 2016-02-22.
  28. ^ Placing documents into the public domain by Daniel J. Bernstein on "Most rights can be voluntarily abandoned ('waived') by the owner of the rights. Legislators can go to extra effort to create rights that can't be abandoned, but usually they don't do this. In particular, you can voluntarily abandon your United States copyrights: 'It is well settled that rights gained under the Copyright Act may be abandoned. But abandonment of a right must be manifested by some overt act indicating an intention to abandon that right. See Hampton v. Paramount Pictures Corp., 279 F.2d 100, 104 (9th Cir. 1960).' " (2004).
  29. ^ Lawrence Rosen (2012-03-08). "(License-review) (License-discuss) CC0 incompliant with OSD on patents, (was: MXM compared to CC0)". Archived from the original on 2016-03-12. Retrieved 2016-02-22. The case you referenced in your email, Hampton v. Paramount Pictures, 279 F.2d 100 (9th Cir. Cal. 1960), stands for the proposition that, at least in the Ninth Circuit, a person can indeed abandon his copyrights (counter to what I wrote in my article) – but it takes the equivalent of a manifest license to do so. :-) [...] For the record, I have already voted +1 to approve the CC0 public domain dedication and fallback license as OSD compliant. I admit that I have argued for years against the "public domain" as an open source license, but in retrospect, considering the minimal risk to developers and users relying on such software and the evident popularity of that "license", I changed my mind. One can't stand in the way of a fire hose of free public domain software, even if it doesn't come with a better FOSS license that I trust more.
  30. ^ Watt, Richard (September 26, 2014). Handbook on the Economics of Copyright: A Guide for Students and Teachers. Edward Elgar Publishing. ISBN 9781849808538. Retrieved 2015-01-11.
  31. ^ Pollock, Rufus (2007-10-01). "OPTIMAL COPYRIGHT OVER TIME: TECHNOLOGICAL CHANGE AND THE STOCK OF WORKS" (PDF). University of Cambridge. Archived from the original (PDF) on 2013-02-21. Retrieved 2015-01-11.
  32. ^ Pollock, Rufus (2009-06-15). "FOREVER MINUS A DAY? CALCULATING OPTIMAL COPYRIGHT TERM" (PDF). University of Cambridge. Archived from the original (PDF) on 2013-01-12. Retrieved 2015-01-11. The optimal term of copyright has been a matter for extensive debate over the last decade.
  33. ^ "Downloads". Creative Commons. 2015-12-16. Retrieved 2015-12-24.
  34. ^ Version 1.0 license on
  35. ^ "11/17: Lulan Artisans Textile Competition". 18 June 2009.
  36. ^ Validity of the Creative Commons Zero 1.0 Universal Public Domain Dedication and its usability for bibliographic metadata from the perspective of German Copyright Law by Till Kreutzer, attorney-at-law in Berlin, Germany.
  37. ^ The unlicense a license for no license Archived 2017-01-22 at the Wayback Machine on by Joe Brockmeier (2010)
  38. ^ The Unlicense Archived 2018-07-08 at the Wayback Machine on
  39. ^ a b Balter, Ben (2015-03-09). "Open source license usage on". Retrieved 2015-11-21. 1 MIT 44.69%, 2 Other 15.68%, 3 GPLv2 12.96%, 4 Apache 11.19%, 5 GPLv3 8.88%, 6 BSD 3-clause 4.53%, 7 Unlicense 1.87%, 8 BSD 2-clause 1.70%, 9 LGPLv3 1.30%, 10 AGPLv3 1.05% (30 mill * 2% * 17% = 102k)
  40. ^ "BSD 0-Clause License (0BSD) Explained in Plain English". Retrieved 25 February 2020.
  41. ^ "Alan Turing at 100". Harvard Gazette. 13 September 2012. Retrieved 2016-02-22.
  42. ^ The Genealogy of Eliza by Jeff Shrager
  43. ^ history-of-spice on "The origin of SPICE traces back to another circuit simulation program called CANCER. Developed by professor Ronald Rohrer of U.C. Berkeley along with some of his students in the late 1960s, CANCER continued to be improved through the early 1970s. When Rohrer left Berkeley, CANCER was re-written and re-named to SPICE, released as version 1 to the public domain in May of 1972. Version 2 of SPICE was released in 1975 (version 2g6—the version used in this book—is a minor revision of this 1975 release). Instrumental in the decision to release SPICE as a public-domain computer program was professor Donald Pederson of Berkeley, who believed that all significant technical progress happens when information is freely shared. I for one thank him for his vision."
  44. ^ Classic Games on "Space War (Asteroids) - Steve Russell – MIT - Tech Model Railroad Club (TMRC) - PDP-1 In 1961, the game that would eventually become Asteroids started life, humbly, at MIT (Massachusetts Institute of Technology). [...] It was also open source, so the code was public domain, available for anybody to utilize and improve upon."
  45. ^ Compute-Gazette-Issue-11-01.pdf
  46. ^ Transactor_v8i3.pdf: "though our disk labels show a copyright notice, up until this issue we stated right on our policies page (page 2) that our programs are 'public domain; free to copy, not to sell'. This notice goes back about 4 years – a popular phrase originally designed to prevent one's program from being 'acquired' by someone in the software business".
  47. ^ 334 PD projects on (February 2016)
  48. ^ Anwesha Das (22 June 2016). "Software Licenses in Fedora Ecosystem". Retrieved 2016-06-27. In the above bar-chart I have counted GPL and its different versions as one family, and I did the same with LGPL too. From this diagram it is very much clear that the MIT License is the most used license, with a total number of use case of 2706. Therefore comes GPL (i.e GNU General Public License) and its different versions, BSD, LGPL (i.e. GNU Lesser General Public License) and its different versions, ASL (i.e Apache Software License) family, MPL (i.e. Mozilla Public License). Apart from these licenses there are projects who has submitted themselves into Public Domain and that number is 137.
  49. ^ douglascrockford on GitHub
  51. ^ disclaimer on
  52. ^ SERPENT - A Candidate Block Cipher for the Advanced Encryption Standard "Serpent is now completely in the public domain, and we impose no restrictions on its use. This was announced on the 21st August at the First AES Candidate Conference." (1999)
  53. ^ copyright on
  54. ^ copyrights-and-licensing on
  55. ^ "youtube-dl GitHub page". GitHub. Retrieved 2 October 2016.
  56. ^ Igor Pavlov (2008). "LZMA SDK (Software Development Kit)". Retrieved 2013-06-16.
  57. ^ tinyspeck (2013-11-18). "Glitch is Dead, Long Live Glitch! - Art & Code from the Game Released into Public Domain". Retrieved 2013-12-11. The entire library of art assets from the game, has been made freely available, dedicated to the public domain. Code from the game client is included to help developers work with the assets. All of it can be downloaded and used by anyone, for any purpose.
  58. ^ Blackwell, Laura (2013-11-18). "Afterlife of an MMO: Glitch's offbeat art enters public domain". Retrieved 2013-12-11.
  59. ^ in mainReference.c: "The Keccak sponge function, designed by Guido Bertoni, Joan Daemen, Michaël Peeters and Gilles Van Assche. For more information, feedback or questions, please refer to our website:[permanent dead link] by the designers, hereby denoted as 'the implementer'. To the extent possible under law, the implementer has waived all copyright and related or neighboring rights to the source code in this file.".
  60. ^ Chalk, Andy (10 January 2023). [1]. PC Gamer. Future plc. Archived from the original on 2023-01-10. Retrieved 30 April 2024.
  61. ^ Skipping Steam: Why Jason Rohrer independently distributes One Hour, One Life on Gamasutra by Richard Moss "you're paying for an account on the server that I'm running. [...], and it's actually in the public domain — the source code's all available." (on August 30, 2018)