Supposed I have written a software that I offer using a dual-license model, using AGPLv3 as OSS license, and a proprietary one as commercial (closed) license.

Now, let's assume somebody wants to contribute something to the software. What do I have to watch out for if I want to be able to use the contribution for the AGPL as well as for the proprietarily licensed code?

In other words: What should I point out in my CLA? Do I need any other contract with the contributor? What are the typical pitfalls to watch out for?

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    You'd want to make pretty clear that you're in essence accepting donations of code for your closed source project, because most people probably won't want to contribute to that if their code is included in both versions. It would most likely also need to be a copyright assignment agreement rather than a contributor license agreement. – curiousdannii Jun 28 '16 at 13:11
  • Would things be different in your opinion if the commercial one was not closed-source, i.e. the source is still available, just with a commercial license? – Golo Roden Jun 29 '16 at 6:53
  • No, that makes pretty much no difference. – curiousdannii Jun 29 '16 at 8:04

In other words: What should I point out in my CLA? Do I need any other contract with the contributor? What are the typical pitfalls to watch out for?

In order to offer both licenses, you would need to be and stay the primary or sole copyright holder. You would effectively need a CLA where contributors grant you enough rights to relicense using both licenses or assign the copyrights to you. You would not be able to accept contributions under the AGPL license.

An example would be the MongoDB CLA.

On a side note, this would create some really weird asymmetry and might be a strong deterrent to any community contribution. Something that I would likely not use.

  • > "Something that I would likely not use" — that sounds weird to me. You do use StackOverflow, although it's closed source. And if they made SO available under AGPL, you're kind of saying that then you'd stop using SO. Maybe you meant you wouldn't contribute to such an OSS project (rather than not use) (?). – KajMagnus Jul 5 '18 at 5:20
  • Indeed, this was not clear! I meant that an asymmetric CLA would be something I would likely not use. I was not talking about about the code or the license but the CLA. – Philippe Ombredanne Jul 5 '18 at 8:40

Another example could be found in Digium's Asterisk project : https://issues.asterisk.org/jira/secure/DigiumLicense.jspa

For more information on this topic of accepting contributions on dual licensed projects, I found the reading of this article of the CivicCommons wiki worth a read: http://wiki.civiccommons.org/Contributor_Agreements/ . In particular, it provides a detailed explanation of the difference between Contributor License Agreement (CLA) and Copyright Assignment Agreement (CAA). Best extract:

Which one should you use?

The short answer is: CLA.

For government projects, we recommend CLA rather than CAA, because a CLA is physically easier for contributors (it can be submitted by email or web form) and because some contributors may sign more readily when no actual transfer of ownership is involved.

CAAs, on the other hand, are mainly requested by private-sector corporations who seek to consolidate copyright ownership. There are various reasons why a corporation might want that. The most common are that it can simplify assertion of copyright internationally, and it can enable “dual-licensing” models where the corporation makes the software available under proprietary terms, for a fee, to customers who need exclusivity for one reason or another (such as marketing a proprietary product derived from the code base). But the transfer of ownership involved in a CAA, along with the possibility of dual-licensing, makes it harder to persuade some contributors to sign, even when the CAA contains a “license-back” provision ensuring that the contributor retains all meaningful rights with respect to their own changes, or even when it contains a promise to only distribute the assigned works under open source terms.

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