Open Source is defined by the OSI's Open Source Definition March 1, 2022 on Drew DeVault's blog

The Open Source Initiative (OSI) publishes a document called the Open Source Definition (OSD), which defines the term “open source”. However, there is a small minority of viewpoints within the software community which wishes that this were not so. The most concerning among them are those who wish open source was more commercially favorable to themselves, and themselves alone, such as companies like Elastic.

I disagree with this perspective, and I’d like take a few minutes today to explore several of the most common arguments in favor of this view, and explain why I don’t agree with them. One of the most frustrating complications in this discussion is the context of motivated reasoning (relevant xkcd): most people arguing in favor of an unorthodox definition of “open source” have a vested interest in their alternative view.1 This makes it difficult to presume good faith. For example, say someone wants to portray their software as open source even if it prohibits commercial use by third parties, which would normally disqualify it as such. Their interpretation serves to re-enforce their commercialization plans, providing a direct financial incentive not only for them to promote this definition of “open source”, but also for them to convince you that their interpretation is valid.

I find this argument to be fundamentally dishonest. Let me illustrate this with an analogy. Consider PostgreSQL. If I were to develop a new program called Postgres which was similar to PostgreSQL, but different in some important ways — let’s say it’s a proprietary, paid, hosted database service — that would be problematic. The industry understands that “Postgres” refers to the popular open source database engine, and by re-using their name I am diluting the brand of Postgres. It can be inferred that my reasoning for this comes from the desire to utilize their brand power for personal commercial gain. The terms “Postgres” and “PostgreSQL” are trademarked, but even if they were not, this approach would be dishonest and ethically wrong.

So too are the attempts to re-brand “open source” in a manner which is more commercially exploitable for an individual person or organization equally dishonest. The industry has an orthodox understanding of the meaning of “open source”, i.e. that defined by the Open Source Initiative, which is generally well-understood through the proliferation of software licenses which are compatible with the OSD. When a project describes itself as “open source”, this is a useful short-hand for understanding that the project adheres to a specific set of values and offers a specific set of rights to its users and contributors. When those rights are denied or limited, the OSD no longer applies and thus neither does the term “open source”. To disregard this in the interests of a financial incentive is dishonest, much like I would be dishonest for selling “cakes” and fulfilling orders with used car tires with “cake” written on them instead.

Critics of the OSD frequently point out that the OSI failed to register a trademark on the term “open source”, but a trademark is not necessary for this argument to hold. Language is defined by its usage, and the OSD is the popular usage of the term “open source”, without relying on the trademark system. The existence of a trademark on a specific term is not required for language which misuses that term to be dishonest.

As language is defined by its usage, some may argue that they are as entitled as anyone else to put forward an alternative usage. This is how language evolves. They are not wrong, though I might suggest that their alternative usage of “open source” requires a substantial leap in understanding which might not be as agreeable to those who don’t stand to benefit financially from that leap. Even so, I argue that the mainstream definition of open source, that forwarded by the OSI, is a useful term that is worth preserving in its current form. It is useful to quickly understand the essential values and rights associated with a piece of software as easily as stating that it is “open source”. I am not prepared to accept a new definition which removes or reduces important rights in service of your private financial interests.

The mainstream usage of “open source” under the OSD is also, in my opinion, morally just. You may feel a special relationship with the projects you start and invest into, and a sense of ownership with them, but they are not rightfully yours once you receive outside contributions. The benefit of open source is in the ability for the community to contribute directly to its improvements — and once they do, the project is the sum of your efforts and the efforts of the community. Thus, is it not right that the right to commercial exploitation of the software is shared with that community? In the absence of a CLA,2 contributors retain their copyright as well, and the software is legally jointly owned by the sum of its contributors. And beyond copyright, the success of the software is the sum of its code along with the community who learns about and deploys it, offers each other support, writes blog posts and books about it, sells consulting services for it, and together helps to popularize it. If you wish to access all of these benefits of the open source model, you must play by the open source rules.

It’s not surprising that this would become a matter of contention among certain groups within the industry. Open source is not just eating the world, but has eaten the world. Almost all software developed today includes substantial open source components. The open source brand is very strong, and there are many interests who would like to leverage that brand without meeting its obligations. But the constraints of the open source definition are important, played a critical role in the ascension of open source in the software market, and worth preserving into the future.

That’s not to say that there isn’t room for competing ideologies. If you feel that the open source model does not work for you, then that’s a valid opinion to hold. I only ask that you market your alternative model honestly by using a different name for it. Software for which the source code is available, but which does not meet the requirements of the open source definition, is rightfully called “source available”. If you want a sexier brand for it, make one! “Open core” is also popular, though not exactly the same. Your movement has as much right to success as the open source movement, but you need to earn that success independently of the open source movement. Perhaps someday your alternative model will supplant open source! I wish you the best of luck in this endeavour.

A previous version of this blog post announced that I had submitted my candidacy for the OSI board. Due to unforseen circumstances, I will be postponing my candidacy until the next election. I apologise for the confusion.


  1. Am I similarly biased? I also make my living from open source software, but I take special care to place the community’s interests above my own. I advocate for open source and free software principles in all software, including software I don’t personally use or benefit from, and in my own software I don’t ask contributors to sign a CLA — keeping the copyrights collectively held by the community at large, and limiting my access to commercialization to the same rules of open source that are granted to all contributors to and users of the software I use, write, and contribute to. ↩︎

  2. Such CLAs are also unjust in my view. Tools like the Developer Certificate of Origin are better for meeting the need to establish the legitimate copyright of open source software without denying rights to its community. ↩︎

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