On dual-licensing

Yesterday at the call we briefly discussed the possibility of implementing the open-core model for Yukon to ensure financial sustainability of the project. There was a related suggestion to consider a dual-license model widely used in some other software products like Qt or iText. Open-core and dual-licensing are not mutually exclusive. Here I want to check if the latter is a viable option for us.

I ventured to ask if there are any established licensing practices such that the software is entirely free to use by individuals but for-profit organizations are incentivized to contribute:

…whereby I was politely informed that the question has already been asked before. Generally, dual-licensing is recommended in such cases instead of drafting up one’s very own license with cleverly engineered built-in restrictions. The default license (the free license) is generally chosen to be highly restrictive, the recommended options are:

  • Affero GPL [tl;dr]. This option does not prevent commercial use but makes it sufficiently difficult for a company to make the secondary (non-free) license a desirable choice.

  • CC BY-NC-SA (Attribution + Noncommercial + ShareAlike) [tldr]. As the name suggests, commercial use is directly prohibited. This license is generally not recommended for software but I am not sure if this is a problem in our specific case.

The long list of well-known licenses on the OSI website does not reveal anything that seems more suitable.

The big question here is this: are we going to shoot ourselves in the foot by using a strong copyleft license as the default license for Yukon? If yes, does it mean that the dual-licensing is not suitable for Yukon?


Dual licensing is not suitable. Open-core shouldn’t need it. Licenses like Affero GPL were designed to handle SaS use of freemium OSS. Yukon doesn’t have that concern. Given the robotics/aerospace/automotive domain; I think the potential to focus on is enabling software consultancies to provide professional services on top of the Yukon framework. To enable this both the consultancy and the customer need to retain ownership rights as negotiated in their service agreement.

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A short caveat at the start: I am not a lawyer, especially not a open source laywer. However, I’m (unsuccessfully) dual-licensing an open source product myself and know another person who’s doing it successfully.

However, there is a crucial difference between those oss projects and Yukon: Yukon is a tool which is used as-is. Therefore using even the most restrictive copyleft won’t make any difference. As per my understanding you can take anyones GPL’d code, compile it, put a price tag on it and sell it. You just have also to hand over the source with the binary and have to provide any modifications or extensions under the GPL too. I therefore suggest to create a financial model around (priority) support and customization.

Edit: Basically I second @scottdixon 's consultancy approach.

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MIT license it is then.

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