Should the user of the code consider the software useful, they are encouraged to buy the author a beer "in return" if they ever meet. The Humanitarian-FOSS project at Trinity College recognized the "version 42" beerware license variant as an extremely permissive "copyright only" and GPL-compatible license.[3] According to the Free Software Foundation the license would be classified as an "informal" free, non-copyleft and GPL-compatible license, however more detailed licenses are recommended.[2]
Poul-Henning Kamp states preference of his Beerware license to other licenses, such as BSD and GPL, the latter of which he has described as a "joke".[4] The full text of Kamp's license is:[5]
/*
* ----------------------------------------------------------------------------
* "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
* ----------------------------------------------------------------------------
*/
Notes
^The earliest revision on the Wayback Machine of the website of Poul-Henning Kamp that contains the license was from that year. If that is indeed the earliest publication of the license is unknown.[1]
^ ab"Beerware License". Humanitarian-FOSS. Archived from the original on 2016-03-22. Retrieved 2015-04-20. The license is compatible with proprietary licenses and the GNU GPL, as code under this license has no restrictions whatsoever.