Chris Fei: Beerware License

/*
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 */

The Beerware License was written by Poul-Henning Kamp, a Danish software developer. Kamp primarily works on the FreeBSD project for which he has made thousands of commits to the kernel over the years. The term was coined in 1987 by John Bristor, but Kamp’s license remains the most well known. Kamp developed his Beerware License partly as a joke, and partly to speak out against the GNU Licenses. In his own words,

“I have had it with lawyers trying to interpret freedom. If I write software which I intend to give away, I don't want to have to stick several pages of legalese on it to make sure nobody exploits it or any such meta-bable. If I have decided that I'll give away some code I've written, I going to give it away, period, none of this "unless it is worth a million to somebody" rubbish. I think the GNU license is a joke, it fights the capitalism it so much is against with their own tools, and no company is ever going to risk any kind of proximity to so many so vague statements assembled in a license.”

The Beerware License is short and to the point. Code licensed under the Beerware License still grants copyright to the author but it is so permissive, the code is effectively in the public domain. That is, anybody can do anything they want with it. There is, however, an optional clause where if a user feels that a work under this license is “worth it”, he or she is encouraged to buy the author a beer if the two ever cross paths. The Beerware License is still free though because buying a beer for the author isn’t actually a requirement. Beerware is both a free license and an open source license, but my research has proven inconclusive regarding whether or not the license is “certified” by the FSF or OSI. The lack of information leads me to believe that it is not certified by either. The license is compatible with proprietary licenses and the GNU GPL, as code under this license has no restrictions whatsoever.