Does a time-based GPL license already exist?

| | August 6, 2015

I would like to find a compromise between totally open source (which is not easy for professional developers on the economical point of view) and totally closed source (which is not nice for the entire world).

I am thinking about releasing my next source code library under a kind of time-based GPL (Time-GPL) license. Here is how I define this Time-GPL license:

“Same as GPL, except that the contraints of providing the source code only apply after a specific duration (described in the license) after the first re-distribution of the binaries based on open source software under the Time-GPL license.”

Using such license, developers who re-use the source code for their commercial project and would be able to make money with their closed source software during a specified period of time (for example, 6 months or 1 year), and then would have the obligation of making the source code available to the public.

Question: Does such a license already exist?

6 Responses to “Does a time-based GPL license already exist?”

  1. The answer is no: Such license doesn’t exist already.

  2. If I understand it correctly, your library is under GPL with an exception allowing developers distribute binary only versions of your library.

    This is easy to do, you can distribute your own code under two licences: Distribute it under GPL and distribute it under a closed source license. Your specific closed source license would allow customers to distribute binary only copies of your library for a limited time. When your binary license runs out only the pure GPL applies.

    There are a number of projects which are GPL and “closed source compatible” for a fee.

    Things only start to get complicated, when you want to accept 3rd party code in your library: Contributors to your library need to contribute in a way that enables you to distribute their work as GPL and as closed source. How this is done (Assigning copyright, usage rights, …) is dependent on the country you live in. IANAL, but to my knowledge Copyright can be “assigned” in the USA whereas “Urheberrecht” is not assignable here in Germany (only usage rights).

    So if you work alone it’s probably easy (use two licenses) and never accept any 3rd party code.

    Other than that: Get a lawyer!

    (and read Wikipedia: Multi Licensing, Business models for open source software lists commercial open source examples)

  3. It’s an interesting idea. I haven’t heard of such a license, but why not just release the software as proprietary to start with, but have a donation fund for release to GPL. Or release the previous stable version as GPL when you launch a new stable version.

    I suspect the answer is that you wish to attract a developer base who can build on the code and benefit themselves for a time. The problem with this is if they stop distributing their modified program before the time constraint comes into effect, they won’t be bound by the GPL anymore.

    I’m not a lawyer, but I understand that licenses like the GPL were developed with advice from legal professionals, so if you want a new license that hasn’t previously existed, you might need to seek similar legal advice.

  4. It looks like a “free to evaluate” license. This is useful for trying something out, but not for building on it.

    Because there are no software patents there’s a strong relation between code openness and the licensing schema. If not, you could let anyone see the code and still hold the license to it.

    Keeping that in mind, there’s no point in letting people see the code and then forcing a license. Your code will get stolen, there’s no protection to it.

    What most companies do regarding this, is to have two code sources. One is open source and offer some basic and general functionality, this normally is also “open-developed” (which is indeed a different paradigm). They retain the intellectual property of a particular instance of the code (more functionality and/or a more specialized case).

    think about Goggle’s MapReduce (Hadoop). They basically open sourced the API and a basic implementation, and they use a similar one (though not the same) internally.

  5. While your idea is to provide flexibility, the onus on the user to prove that he did use it after that point in time would become an issue. Instead release a version with a “different” license after that point in time when you think it is correct to do so. You can have both licenses applicable to your software.

  6. Charles Menguy on November 30, -0001 @ 12:00 AM

    From what I’ve seen in the past, the only kinds of licenses that come close to what you’re describing would be for software with “evaluation periods”.

    So basically your software would be proprietary, but with an “evaluation period” of several months for example.

    You can see an example of what I mean here

    I don’t think otherwise there exists any kind of software license where you have to open-source it after a given period and I wouldn’t personally find it very appealing: if I’m making money with a software but that at some point I have to open-source it, the software will just become pointless.

    Hope that helps.

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