I've searched the web for information about this, but haven't found a clear answer, that I understand at least.

I have created an Flask app, which utilizes libraries such as Pandas, NumPy, Scikit Learn and some others. This app is eventually meant to be used for commercial use mainly.

Do I have to add their licenses somewhere, when I only import the libraries, and not redistributing their code? If so, where? Since it's not open source and it is a web app, do I need to add it somewhere on my site, is it any best standards to where?

I would like to credit these libraries anyway, but I just want to be sure I'm not doing anything wrong.

Also one of the functions is to deliver back files in e.g. Excel formats, PDF and PowerPoint, do I need to do anything with licenses regarding this? Since two of them are Microsoft owned.

Any help is greatly appreciated!

1 Answer 1


Note: I am not Lawyer and nothing below is legal advice.

  1. Each library is likely to have its own license.
  2. Some licenses (GPL, for instance) would require you to opensource your code should you use libraries under such license.
  3. Depending on the license, you may (or may not) be required to give a credit or state author(s) copyright in some way.
  4. For instance, Flask has BSD License. Summary for BSD license can be found here: https://tldrlegal.com/license/bsd-3-clause-license-(revised).
  5. As one of the options of giving credit, one may consider listing all the used libraries somewhere (at the footer, at a specific page on the web site, etc.) with links and all the relevant information.
  • 1
    Re point 5: If something is a "derivative work" or not is independent of if you are distributing the work or not. The Python code of the application is probably a derivative work of Flask, but that does not mean that much until you distribute the application. Mar 3, 2020 at 11:56
  • @BartvanIngenSchenau I had an impression that it is a derivative work only if I change the original code of Flaks and use/distribute it. Mar 3, 2020 at 18:28
  • 2
    If you "build upon" an existing work, then that also creates a derivative work. In terms of software works, using a library/framework is considered to fall under "build upon". Note that this interpretation is required for the strong copyleft nature of the GPL to be enforceable. Mar 4, 2020 at 7:48
  • @BartvanIngenSchenau I see. Thank you for clarification, I will update my answer! Mar 4, 2020 at 10:07

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