Unlicense


The Unlicense is a public domain equivalent license with a focus on an anti-copyright message. It was first published on January 1, 2010. The Unlicense offers a public domain waiver text with a fall-back public-domain-like license, inspired by permissive licenses but without an attribution clause. In 2015, GitHub reported that approximately 102,000 of their 5.1 million licensed projects use the Unlicense.

History

In a post published on January 1, 2010, Arto Bendiken outlined his reasons for preferring public domain software, namely: the nuisance of dealing with licensing terms, the threat inherent in copyright law, and the impracticability of copyright law.
On January 23, 2010, Bendiken followed-up on his initial post. In this post, he explained that the Unlicense is based on the copyright waiver of SQLite with the no-warranty statement from the MIT License. He then walked through the license, commenting on each part.
In a post published in December 2010, Bendiken further clarified what it means to "license" and "unlicense" software.
On January 1, 2011, Bendiken reviewed the progress and adoption of the Unlicense. He admits that it is "difficult to give estimates of current Unlicense adoption" but suggests there are "many hundreds of projects using the Unlicense".

License terms

The license terms of the Unlicense is as follows:
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or
distribute this software, either in source code form or as a compiled
binary, for any purpose, commercial or non-commercial, and by any
means.
In jurisdictions that recognize copyright laws, the author or authors
of this software dedicate any and all copyright interest in the
software to the public domain. We make this dedication for the benefit
of the public at large and to the detriment of our heirs and
successors. We intend this dedication to be an overt act of
relinquishment in perpetuity of all present and future rights to this
software under copyright law.
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 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.
For more information, please refer to <http://unlicense.org/>

Reception

The Free Software Foundation states that "Both public domain works and the lax license provided by the Unlicense are compatible with the GNU GPL." However, for dedicating software to the public domain it recommends CC0 over the Unlicense, stating that CC0 "is more thorough and mature than the Unlicense".
The Fedora Project recommends CC0 over the Unlicense because the former is "a more comprehensive legal text".
In December 2010, Mike Linksvayer, the vice president of Creative Commons at the time, wrote in an identi.ca conversation "I like the movement" in speaking of the Unlicense effort.
The Unlicense has been criticized, for instance by the OSI, for being possibly inconsistent and non-standard, and for making it difficult for some projects to accept Unlicensed code as third-party contributions; leaving too much room for interpretation; and possibly being incoherent in some legal systems.
Notable projects that use the Unlicense include youtube-dl and Second Reality.