I have one web application A that generates some logs files. The application A may have a GPL-v3 or GPL-v2 license. I want to create a custom application B to read logs of the application A.

My question is, must the application B be licensed with GPL-v2/v3 or not?

2 Answers 2


The GPL on Application A refers (usually, you should probably check) only to the program, and not to any data it produces. It is possible that the data files are covered, but in that case there would have to be notice of that in the data file. If there isn't, then (my understanding is) that you (or whoever "owns" the copy of A that wrote the log) is the producer and thus the copyright owner (per Berne). If all that applies, then you are allowed to do whatever you want with the log files.

As usual: IANAL, TINLA.

  • Thanks :) Ill wait until more answer. When I read GPL doc, I have this feeling ; while I don't modify the behaviour of the application, my application B must not be in GPL license. Commented Jul 3, 2016 at 7:02
  • You sound reluctant to put your own code under GPL. I think that's a bad choice. The most common reason for thinking you want to not use the GPL is that you might want to do something else later and are worried that having a GPL copy around will make that hard. But see my answer to another question on that subject.
    – MAP
    Commented Jul 5, 2016 at 5:42

In general, log data files written by one application irrespective of its license can be read by software using any other license. The same way you can write a DOCX document with LibreOffice and open it with Microsoft Word and that would not have any impact on the licensing of Microsoft Word.


My question is, must the application B be licensed with GPL-v2/v3 or not?

Absolutely not.

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