I am looking for a copyleft license. My issue with GPLv3 is that it is so hard to understand. I don't want to license my work under terms I do not even understand. Fundamentally, I don't understand it because it, as a strong copyleft license, has to clarify many more legal nuances. So, my thought was to look for a weak copyleft license because I assume these are less complex. I read through MPLv2 and it makes sense and seems great for my purposes. Then I got to section 10.2 and was disappointed:

10.2. Effect of New Versions
You may distribute the Covered Software under the terms of the version of the License under which You originally received the Covered Software, or under the terms of any subsequent version published by the license steward.

Essentially, this means Mozilla can change what copiers can do at any time. I think this is horrible. I am looking for a solution to this problem:

  1. I could remove section 10.2 and rename the license per section 10.3:

    10.3. Modified Versions If you create software not governed by this License, and you want to create a new license for such software, you may create and use a modified version of this License if you rename the license and remove any references to the name of the license steward (except to note that such modified license differs from this License).

    According to this answer the primary downside to doing so would essentially be that Mozilla could potentially be disinclined to provide legal council to me if requested. Is a modification like this advisable?

  2. I could find another license. I have searched but haven't found a similar one. What is a similar license that doesn't have this bad clause?

  • 2
    Whatever license you choose, modified or not, no-one will ever be obliged to provide legal council to you, also not Mozilla, unless you pay them to do so specifically. Commented Jul 22, 2021 at 19:15
  • @planetmaker see I found that comment weird because I never thought there was even an implication of support from the license writer, let alone obligation
    – user24638
    Commented Jul 22, 2021 at 19:25
  • @anonomos there isn't. The linked answer isn't from this board and has a number of substantive errors in it, so I wouldn't put too much faith in it.
    – MadHatter
    Commented Jul 22, 2021 at 19:42
  • Could you clearify what you mean by "strong copyleft" vs. "weak copyleft".
    – Brandin
    Commented Jul 26, 2021 at 7:57
  • See also Copyleft explanation by GNU, as well as their list of various licenses and whether/not they are copyleft.
    – Brandin
    Commented Jul 26, 2021 at 8:04

1 Answer 1


The fundamental problem with all copyleft licences is that they have to have a fair amount of legal boilerplate in them. GPLv2 puts it rather well, to my mind, when it says in the preamble

To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.

Restricted copyleft licences are likely to be as least as bad, since they now have to define the bits of the software that are copylefted, instead of just "all".

If you want a simple licence, go permissive. If you want a copyleft licence, the GPL is actually pretty simple to work with, provided you're not trying to play fast and loose with it: make sure that everyone who gets a copy of your binary also gets the complete source code, and make sure that it's clear they get all of it under GPL, and you'll be fine.

Don't, however, start making up your own licences. If you do, then for all practical purposes you might as well not bother freeing your software, because most people who will think about reusing it aren't going to parse the licence either. Everyone out there understands the major copyleft and permissive licences, so they can sidestep reading them when they see the licence tag. If they have to stop and research what Anonomos Public Licence v1.35 lets them do, they're not going to bother.

  • Your first four paragraphs are essentially repeating my third sentence. I understand why copyleft licenses are more verbose. I'm looking for an easily readable copyleft license that doesn't have something like the MPLv2's section 10.2.
    – user24638
    Commented Jul 22, 2021 at 19:32
  • My first two paragraphs are telling you why you can't have an easily-readable copyleft licence, strong or weak.
    – MadHatter
    Commented Jul 22, 2021 at 19:34
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    I can't tell you what you do and don't find readable. I can only tell you that copyleft licences are a lot longer than permissive ones, and for good reason. If you think the GPL is complex, that's a shame, but since you haven't said which bits you find hard to understand we can't discuss that. If you like the MPL more, then great, by all means use it. If you're hoping for a simpler copyleft licence, then good luck, though I don't think you'll find it. But please don't use a crayon licence: you're doing nobody any favours, yourself included, if you do.
    – MadHatter
    Commented Jul 22, 2021 at 19:43
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    You asked two questions, as I see it, and I think I've answered both. 1) no, because it's a crayon licence. 2) I don't think there is one.
    – MadHatter
    Commented Jul 22, 2021 at 20:05
  • 1
    Consider David A. Wheeler's advise: "Make your open source software GPL-compatible. Or else."
    – vonbrand
    Commented Jul 24, 2021 at 22:22

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