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Why has GPL license usage dropped dramatically?
The decline of GPL?
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A little while ago I saw an interesting tweet from Stephen O'Grady at RedMonk on the state of open source licensing, including this graph.
This graph shows how license usage has changed from 2010 to 2017. In reading it, it is clear that usage of the GPL 2.0 license, one of the purest copyleft licenses around, has more than halved in usage. According to the chart it would appear that the popularity of open source licensing has subsequently shifted to the MIT and Apache licenses. There has also been a small increase in GPL 3.0 usage.
So, what does all this mean?
Why has GPL 2.0 usage dropped so dramatically with only a marginal increase in GPL 3.0 usage? Why has MIT and Apache usage grown so dramatically?
Of course, there are many interpretations, but my guess is that this is due to the increased growth in open source in business, and a nervousness around the GPL in the commercial world. Let's dig in.
The GPL and business
Now, before I get started, I know I am going to raise the ire of some GPL fans. Before you start yelling at me, I want to be very clear: I am a huge fan and supporter of the GPL.
I have licensed every piece of software I have ever written under the GPL, I have been an active financial supporter of the Free Software Foundation and Software Freedom Conservancy and the work they do, and I advocate for the usage of the GPL. My comments here are not about the validity or the great value of the GPL—it is an unquestionably great license—but more about the perception and interpretation of the license in the industry.
About four years ago, I was at an annual event called the Open Source Think Tank. This event was a small, intimate, annual gathering of executives in the open source industry in the California wine country. The event focused on networking, building alliances, and identifying and addressing industry problems.
At this event, there was a group case study in which the attendees were broken into smaller groups and asked to recommend an open source license for a real-world project that was building a core open source technology. Each group read back their recommendations, and I was surprised to see that every one of the 10 or so groups suggested a permissive license, and not one suggested the GPL.
I had seen an observational trend in the industry towards the Apache and MIT licenses, but this raised a red flag at the time about the understanding, acceptance, and comfort of the GPL in the open source industry.
It seems that in recent years that trend has continued. Aside from the Black Duck research, a license study in GitHub in 2015 found that the MIT license was a dominant choice. Even observationally in my work at XPRIZE (where we chose a license for the Global Learning XPRIZE), and my work as a community leadership consultant, I have seen a similar trend with many of my clients who feel uncomfortable licensing their code under GPL.
With an estimated 65% of companies contributing to open source, there has clearly been a growth in commercial interest and investment since 2010. I believe this, tied with the trends I just outlined, would suggest that the industry does not feel the GPL is generally the right choice for an open source business.
Interfacing community and company
To be honest, GPL's declining popularity is not entirely surprising, and for a few reasons.
Firstly, as the open source industry has evolved, it has become clear that finding the right balance of community engagement and a business model that... y'know... actually works, is a key decision. There was a misconception in the early days of open source that, "If you build it, they will come." Sure, they often came to use your software, but in many cases, "If you built it, they wouldn't necessarily give you any money."
As the years have progressed we have seen various companies, such as Red Hat, Automattic, Docker, Canonical, Digital Ocean, and others, explore different methods of making money in open source. This has included distribution models, services models, open core models, and more. What has become clear is that the traditional software scarcity model doesn't work with open source code; therefore, you need to choose a license that supports the needs of the model the company chooses. Getting this balance between revenue and providing your technology for free is a tough prospect for many.
This is where we see the rub. While the GPL is an open source license, it is fundamentally a free software license. As a free software license, much of the stewardship and support for the GPL has been driven by the Free Software Foundation.
As much as I love the work of the Free Software Foundation, their focus has ultimately been anchored from the perspective that software absolutely has to be 100% free. There isn't much room for compromise with the FSF, and even well-recognized open source projects (such as many Linux distributions) have been deemed "non-free" due to a tiny bit of binary firmware.
This proves complicated for businesses where there is rarely a black and white set of choices and there is instead a multitude of grey. Few businesses share the pure ideology of the Free Software Foundation (or similar groups such as the Software Freedom Conservancy), and thus I suspect businesses are less comfortable about choosing a license that is so connected to such a pure ideology.
Now, to be clear, I don't blame the FSF (and similar organizations such as the SFC) for this. They have a specific mandate and mission focused on building a comprehensive free software commons, and it is perfectly reasonable for them to draw their line in the sand wherever they choose. The FSF and SFC do phenomenal work and I will long continue to be a supporter of them and the many wonderful people who work there. I just believe that a consequence of such purity is that companies may feel uneasy being able to meet the mark, and thus chose to use a different choice of license than the GPL.
I suspect what has also affected GPL usage is a change in dynamic as open source has grown. In the early days, one of the core fundamental reasons why projects would start was a rigorous focus on openness and the ethical elements of software freedom. The GPL was unsurprisingly a natural choice for this projects, with Debian, Ubuntu, Fedora, Linux, and many others as examples.
In recent years though we have seen a newer generation of developers form for whom there is a less critical, and if I dare say it, less religious focus on freedom. For them, open source is a pragmatic and practical component in building software as opposed to an ethical choice, and I suspect this is why we have seen such a growth in the use of MIT and Apache licenses.
What does this mean for the GPL?
My guess is that the GPL will continue to be a popular choice of license, but developers will view it increasingly as a purer free software license. I suspect that projects that have an ethical commitment to software freedom will prioritize the GPL over other licenses, but for businesses where there needs to be the balance we discussed earlier, I suspect the MIT and Apache licenses will continue to grow in popularity.
Either way, the great news is that open source and free software is growing, and while there may be complexity and change in how licenses are used, what matters more is that technology is increasingly becoming open, accessible, and available to everyone.