When choosing an open-source license, I’m inclined to use the GPL ‘copyleft’ share-alike style license since it’s the most restrictive, and gives me the option of putting a less restrictive license in the future if I want. Whereas if I release my work with a more permissive license such as BSD or the unlicense, then I will never be able to make it more restrictive if I want. I’ve lost the option.
What are your thoughts on this issue?
The reason why I ask is that I maintain a website for my students to answer questions relevant to the subjects that I teach:
http://www.fightfinance.com
Recently a new teacher took over one of my subjects. I’d like to let her continue using the tutorial questions and answers that I made.
It would be nice to see my work continue to be used after I lose interest in it.
However it would be upsetting if a textbook publisher poached all of my work and wrote a textbook based on the questions and charged students to buy it.
For this reason I’m inclined to use a creative commons attribution share-alike license, which is similar to GPL:
https://creativecommons.org/licenses/by-sa/4.0/
Some background for those who are not familiar with the broad families of licenses:
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Unlicense/creative commons (CC) zero/public domain style licenses. Bitcoin uses the unlicense.
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Apache/BSD/MIT/CC attribution style licenses. BSD unix obviously uses the BSD license.
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Copyleft GPL/CC share-alike, and then copyright. Linux, GNU, Webkit browser (Chrome and Safari), Wikipedia, and Oracle Java (with class path exception) use the GPL license.
Here’s some data on the prevalence of each license:
http://blogs.the451group.com/opensource/files/gplusage.png
Altruistic programmers and authors choose the most permissive licenses which are the public domain or attribution BSD-style license.
Most open source projects use GPL which forces any improvements to the code base to be shared. Businesses dislike contributing to projects with this license since it nullifies any competitive advantage from their investment because they have to share their improvements with potential competitors.
For software that I want to make money from, of course I maintain copyright.
But so far I’ve made no money from any software! So I always end up open-sourcing my work after I realise that I won’t be able to sell it because there are a million free and better alternatives or because I lose interest and then I slap a BSD style license on it.
Jimmy Wales founded Wikipedia, arguable the greatest open-source resource, and has now moved on from there to make private wiki sites for games and other things that he can make money from. That’s quite an interesting switch.