Most Windows installers for FOSS software make the user agree to the licence during installation: there'll be a page where the text is shown and a little tick box, you must have seen it before.

But most FOSS licences put zero restrictions on how you can use licensed software; the licences are all about redistribution. The GPL3 says:

This License explicitly affirms your unlimited permission to run the unmodified Program.

The FSF's Free Software Definition says:

The freedom to run the program as you wish, for any purpose (freedom 0).

And the OSI's Open Source Definition says:

  1. No Discrimination Against Fields of Endeavor
    The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.

So why do so many installers not just tell you about the licence, not just show you the licence, but require you to agree to it before proceeding? 90% of such users will never distribute the software in any form, of those who do most won't do anything other than share the installer on a USB drive. Are there reasons to make the user agree to it, other than it just being what most installers do now?

  • 4
    The makers of the installer want to make it look more like a commercial software? :-)
    – Mnementh
    Jun 24, 2015 at 0:27
  • 2
    I think it is mostly an error on the developers' side. I have opened bug reports for that occasionally, especially if the user is required to accept the license to continue with the installation. Jun 24, 2015 at 5:38

3 Answers 3


I can think of a few reasons:

  • Conflation with EULAs. As you mentioned, copyright licenses deal with redistribution, not usage. EULAs, as their name implies (End User License Agreement), are contracts that restrict your rights as a user, and are therefore something the user must agree to before using the software, and naturally belong in places like the installer.
  • Attribution. Many licenses require that the license text itself is reproduced in redistributions; some licenses also require attributing the original authors. The requirements vary, but many are quite flexible in where the license text appears. For examples, they could be placed in an About dialog, a Readme file, on the Download web page, in the Credits. The installer is just another place to mention those licenses.
  • Convenience. Most software that build installers include a way to embed a custom text file as a step in the installation. For example, NSIS has the function MUI_PAGE_LICENSE textfile in its macro language. This is a much easier way of showing a license than other methods like building an About dialog.
  • Evangelism. Many software developers using FOSS licenses are proud of doing so, and would like to loudly advertise this fact. Making users read this when installing is a good way of doing this.

But ultimately, copyright licenses (like the FOSS ones) do not require "agreeing", only that some require the user be able to read about them somewhere.

  • 2
    NSIS can be trivially configured at built time to put the license page there but not have any "I Agree" button or checkbox; the button simply says "Next". Seems ideal for this.
    – Joshua
    Jan 9, 2022 at 5:27

Some licenses, including the GPLv3, contain a Disclaimer of Warranty and a Limitation of Liability (Sections 14 and 15), which are relevant to using the software.

By having the user agree to the license as if it was an EULA, you are telling him that he waives the right to sue you for (among others) any damage caused by the program.

  • 4
    But there's nothing to agree for a Disclaimer of warranty, and users can still sue if they want to. Jul 19, 2015 at 21:36

Making users accept the FOSS license during installation is a convenient way to fulfill the obligation to inform them about their rights. GPL licenses specifically requires that anyone who distributes the software informs all end users that they are getting GPL software, and not doing so is in itself a violation of GPL.

Indeed, this can be done without making the users accept the license. At the very minimum, GPL requires to appropriately inform users about

  • copyright notice
  • notice that GPL applies to the software, and information about how to get the full license copy
  • disclaimer of warranty

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