I'm a developer who makes open-source software, typically libraries and websites.

My libraries are under the Apache 2.0 license, while websites / applications are under the GPL/AGPL 3 license.

I've been reading into copyright and licensing and understand that contributors retain copyright of their contributions, and that if I hypothetically wanted to change the license later, I'd need the consent of all copyright holders (contributors) to do so.

I have no qualms with this, but I've been wondering if it's practical to provide the means for individuals to voluntarily sign an optional Contributor License Agreement (CLA). The goal is to minimize friction to contributing initially, but to also encourage signing to reduce potential headache should I ever want to change the license, or update to a later version of the current license.

This seems optimal to me, as it grants contributors the choice to grant the right to relicense, while not obligating them to do so just to contribute to the project. However, I've failed to find any projects that do this.

  • 2
    Note that a CLA doesn't transfer copyright, it usually gives relicensing rights (and sometimes other rights also) to the recipient. If you want full transfer of ownership, that's a CTA.
    – MadHatter
    Jul 29, 2019 at 14:50

1 Answer 1


Having an optional CLA is definitely not common, but I also don't see why it might be considered inappropriate. I think the main reasons why it isn't seen are more of a practical nature.

By having a CLA that is optional to sign, you get the administrative burden of keeping track who signed the CLA, but you don't get the benefits of the CLA because when you want to exercise the rights granted there, you still need to track down and contact the (potentially large number of) contributors that didn't sign the CLA.

The main use case for a CLA is to support the situation where a software product is offered both with an open-source license and with a commercial closed-source license and the organisation maintaining the product wants to be able to include open-source contributions also in the closed-source offering.

License changes are very rare, especially if you carefully considered your initial license choice, and most licenses are already prepared for a license upgrade without needing explicit consent from the contributors at the time that the upgrade takes place. For example, the standard license indication for the GPL reads (emphasis mine)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

The bold portion gives anyone permission to use the code under GPLv4, whenever that new version of the GPL appears, because all contributors have already agreed with such a license upgrade.

  • 1
    I see, so if I'm understanding you're saying there is certainly nothing wrong with it. But it may not prove practical as I'll have to manage this list (as well as store personal information) for a rights I'm not even sure I need or want, and would still need to get explicit consent from most people anyways that won't sign it voluntarily?
    – Seth Falco
    Jul 29, 2019 at 10:36
  • Could one still argue it is still worth it in order to reduce total copyright holders to require concent in such an event while not mandating that contributors must give rights or copyright? While I can appreciate your point regarding practicality very well, I also do see it as something that can save hassle to, not just create it?
    – Seth Falco
    Jul 29, 2019 at 10:40
  • 2
    @Seth: I regard it as impractical, but not otherwise wrong. You are free to look differently on the practicality. Just remember that a CLA is a legal document (a contract) and that you have to comply with various data protection regulations (for example the GDPR if you or a contributor who signed the CLA is based in Europe). Much of it probably also depends on what percentage of contributors you expect will sign the CLA. Jul 29, 2019 at 10:47

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