For instance, in Github, can we declare our own license (in LICENSE.txt): "make any use only if you declare the author", or must we choose known ones like GPL3, MIT, etc

  • 6
    Welcome to OS.SE! You should probably read our question on GitHub (and other) software without explicit licences, to see what the implications of not choosing a licence are, and our question on crayon licences, to see what the implications of writing your own licence are. If those two leave you with any unanswered questions, please edit this question to be clearer about what you still want to know; otherwise, please let us know, so we can close this as a duplicate. Thanks!
    – MadHatter
    Jun 3, 2020 at 7:50

1 Answer 1


First, the conditions on GitHub might forbid you doing what you want (unless you pay them). See of course also this.

Second, you need to pay a lawyer to write your own license. AFAIK, the CECILL license required more than a full time year of work to several lawyers. Law is as difficult as programming (and perhaps even more).

Then, if you invent your license, you'll need to negotiate and convince organizations like FSF, OpenSource initiative, APRIL, AFUL to label your license as open source and compatible with existing ones....

In practice, if you invent your license, nobody will use your software

(in a professional setting). In many corporations, it is managers and lawyers who dictate what open source licenses developer can use (even to link an existing open source library).

Please read also this paper on the simple economics of open source.

So make us a favor: don't publish your software with your own license. You'll avoid losing your and perhaps our time.

Don't forget a known fact: even if you develop free software or open source one, you'll have very hard time in attracting users to it. Most code on github is probably almost never used.

I speak of personal experience, being paid to write free software. The most difficult issue is to find real users.

PS. Since you live in France, consider joining AFUL or APRIL -I am member of both- and look into Systematic GTLL. Read J.Tirole's book Économie du Bien Commun (it has a long chapter dedicated to open source software), look online into X.Leroy talks at Collège de France, Roberto DiCosmo website, the Software Heritage initiative, follow Séminaire Code Source, and see RefPerSys. If you want to, please send me an email to [email protected] mentioning the URL of your question.

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    "Law is as difficult as programming (and perhaps even more)." -- Discovering a runtime error in your license terms is certainly much worse, since it takes many thousands of dollars to get an execution environment first. :)
    – apsillers
    Jun 3, 2020 at 17:34
  • 1
    Some bugs costed billions of dollars. Jun 3, 2020 at 19:26

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