I want to use for the creation of an application that I plan to add to Google play (free to use) some code that is licensed under a CC0 license (https://github.com/tedbarnett/read-exif-in-unity). However this code use the work from an other licensed code (CPOL license https://www.codeproject.com/info/cpol10.aspx). I was wondering how I was supposed to deal with this situation: Am I allowed to use the code and if I am how exactly should I proceed to publish my application on Google play.

  • Could you please give some details how the code under CC0 is using the code under CPOL? Is it a direct copy, a dependency, ...? Jan 4, 2022 at 16:21
  • It is a direct copy of the whole CPOL code which is used like a tool for his own code.
    – Elimente
    Jan 4, 2022 at 18:34

1 Answer 1


I drilled down into the project you linked and saw that there is sample code, which is licensed under CPOL 1.0. In your comments to your question you mentioned that this CPOL-licensed code is directly copied into the CC0-licensed project.

I think this should not be. CPOL-licensed code must not be re-licensed as CC0. When you (fork and) re-license you can only reduce freedoms and add restrictions, not the other way around; but CC0 would be removing restrictions compared to CPOL. I believe we are witnessing a license-incompatibility.

If I wanted to use this code (and there is no alternative) I would directly address the re-licensing question with the developers of the 2 projects and ask for their thoughts.

Alternatively you could fork the CC0 project, remove the CPOL code from it, and implement that same CPOL code as a dependency directly in your own project. You can then license your own project with any license that is compatible to CPOL and any other dependencies used in your project.

  • Thank you for the thoughtful response but I am still a bit confuse about the CPOL license... It says I should make sure any user agree with the license so doesn't that mean that I have to provide a link to the original code or just to a copy of the license ? Should I also cite the names of the 2 works I used or can I use them without saying anything ?
    – Elimente
    Jan 5, 2022 at 10:23
  • Most of the terms in the CPOL License only apply to the 'Work' (as defined in the license) but not to 'Derivative Works' (as defined). It will be proper to include a link to the Work and its license in the 'About' page of your App, in the same way that you will need to do that with the other dependencies (I see a lot of Unity dependencies). Jan 5, 2022 at 10:52

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