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I can sell a software which uses an open source library as long as I provide the source of this software with the binaries.

  1. Can I make the source available only to those who bought the software?

  2. Can the customers give the source code to anybody? Will this happen? How is it considered by the open source community?

This question was raised in this discussion. It concerns the GPL license of the CGAL library, but I would like a general answer if possible.

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arthur.sw
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  • This question was raised in [this](http://stackoverflow.com/q/19086109/719276) discussion. It concerns the [GPL license of the CGAL library](http://www.cgal.org/license.html), but I would like a general answer if possible. – arthur.sw Aug 19 '15 at 08:50
  • see [Can I use GPL software in a commercial application](http://programmers.stackexchange.com/questions/47032/can-i-use-gpl-software-in-a-commercial-application) – gnat Aug 19 '15 at 08:53
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    "Can I make the source available only to those who bought the software?" – Yes. "Can the customers give the source code to anybody?" – Yes. "Will this happen?" – You tell me. They're your customers, I don't know them. "How is it considered by the open source community?" – How is what considered by the Open Source community? – Jörg W Mittag Aug 19 '15 at 09:01
  • @gnat: I have seen that before, but I do not see how it answers my questions. I also read the [GNU project article "Selling Free Software"](http://www.gnu.org/philosophy/selling.html), but I still do not understand what is the philosophy of it. – arthur.sw Aug 19 '15 at 09:03
  • @Jörg W Mittag: I wonder (I think am not the only one) what is the philosophy behind open source. Would CGAL authors be offended if I sell an app made with CGAL, and distribute the source with the binaries? Or do they expect this to happen? Because they also have a commercial licence. – arthur.sw Aug 19 '15 at 09:13
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    I cannot read the minds of the CGAL developers. If you want to know what they have to say, ask them. – Jörg W Mittag Aug 19 '15 at 09:21
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    There is no philosophy behind open source, or possibly there are many. This is reflected in the significant number of different OS licenses which vary in what they permit. I've occasionally seen developers get upset about legitimate commercial uses of OS software but in general so long as you're complying with the license terms no-one is going to complain. CGAL say the commercial license exists for cases where "the constraints of the Open Source license prevent you from using CGAL". Doesn't sound like they're bothered about compliant commercial use under GPL. – Nigel Harper Aug 19 '15 at 09:31
  • And thank you @Jörg W Mittag for pointing out that I should ask the authors if I need some precisions. – arthur.sw Aug 19 '15 at 09:38

1 Answers1

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Can I make the source available only to those who bought the software?

Yes. There are no (open-source) licenses that require you to provide the source code to just anybody. The most that is required is that you provide the source code to those people that have obtained a legitimate copy of the software itself.

Can the customers give the source code to anybody? Will this happen?

One of the universal rights that an open-source license grants is the right to redistribute copies of the software that is covered by the license. And an open-source license can't put restrictions on such redistribution, such as a minimum price that must be paid.

So, if you sell software that is under an open-source license, then your customers automatically get the right to redistribute that software and to do so at a lower price that what you charge.
If the software package proves to be popular, then there will almost certainly be people who take advantage of that right.

Now, if your software package uses a library with a copyleft license (for example, the GPL), then your entire software package must be made available under an open-source license. This does not forbid selling the software, but it makes the business case for doing so very weak as each of your customers can undercut your price.

Bart van Ingen Schenau
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    The GPL does require you to provide the source to anybody who asks in one case. One of the options for making the source accessible is to provide a written offer for the source with your software. Anyone who distributes the software must also include a copy of the offer, and [anyone with the offer must get access](https://www.gnu.org/licenses/gpl-faq.html#WhatDoesWrittenOfferValid). This effectively means you'd have to send a copy of the source to anybody who asks if you didn't opt for another source distribution mechanism, e.g. dumping it on GitHub or an anonymous FTP server. – amon Aug 19 '15 at 11:24
  • Very nice, I really appreciate this answer. – arthur.sw Aug 19 '15 at 12:41