The trend towards permissive licensing

Ian Skerrett last week suggested that there is a growing trend in favour of permissive non-copyleft licenses at the expense of reciprocal copyleft licenses. Ian asked “name one popular community open source project created in the last 5 years that uses the AGPL or GPL?”

The responses didn’t exactly come thick and fast. I certainly couldn’t think of one. But the question did prompt me to look for some evidence for the trend away from copyleft licenses.

License usage
The first port of call for evidence of trends related to open source license use is Black Duck’s Open Source Resource Center. The lastest figures show that GPLv2 is used for 45.33% of projects in Black Duck’s KnowledgeBase, while the GPL family accounts for roughly 61% of all projects.

While the GPL family is dominant, comparing the latest figures with those provided in June 2008, June 2009, and some previous CAOS research from March 2010 indicates a steady decline in the use of the GPL family and the GPLv2 in particular.

According to Black Duck’s figures the proportion of open source projects using the GPL family of licenses has fallen to 61% today from 70% in June 2008, while the GPLv2 has fallen to 45% from 58% three years ago.

It is worth noting that the number of projects using the GPL licenses has increased in real terms over the past few years. According to our calculations based on Black Duck’s figures, the number of GPLv2 projects rose 5.5% between June 2009 and June 2011, while the total number of open source projects grew over 16%.

We should expect to see slower growth for the GPLv2 given it has been superseded but even though the number of AGPLv3 and GPLv3 projects grew 90% and 85% respectively over the past two years, that only resulted in 29% growth for the GPL family overall (while A/L/GPLv3 adoption appears to be slowing).

In comparison the number of Apache licensed projects grew 46% over the past two years, while the number of MIT licensed projects grew 152%. Indeed Black Duck’s figures indicate that the MIT License has been the biggest gainer in the last two years, jumping from 3.8% of all projects in June 2009 to 8.23% today, leapfrogging Apache, BSD, GPLv3 and LGPLv2.1 in the process.

While the level of adoption of copyleft licenses remains dominant, and continues to rise in terms of the number of projects, there is no escaping the continuing overall decline in terms of ‘license share’.

UPDATE – Since some people dod not trust Black Duck’s data I also took a look at data collected by FLOSSmole. The results are remarkably similar. – UPDATE

Vendor formation
Black Duck’s data is not the only indication that the importance of copyleft licenses has decreased in recent years. The research we conducted as part of of our Control and Community report also indicated a decline in the number of vendors engaging with strong copyleft licensed software.

Specifically, we evaluated the open source-related strategies of 300 software vendors and subsidiaries, including the license choice, development model, copyright strategy and revenue generator.

By plotting the results of this analysis against the year in which the companies were founded (for open source specialists) or began to engage with open source (for complementary vendors) we are able to gain a perspective on the changing popularity of the individual strategies*.

Having updated the results to the end of 2010, our analysis now covers 321 vendors and shows that 2010 was the first year in which there were more companies formed around projects with non-copyleft licences than with strong copyleft licences.

The formation of vendors around open source software with strong copyleft licenses peaked in 2006, having risen steadily between 1997 and 2006 – although there have been gains since 2007. By comparison, the formation of vendors around open source software with non-copyleft licences has been steadily increasing since 2002.

The results get even more interesting in terms of Ian’s question if we filter them by development model. Looking at community-led development projects, we see that there have been significantly more companies formed around community-led projects with non-copyleft licenses than with strong copyleft licenses since 2007.

In fact, strong copyleft licenses have been much more popular for vendor-led development projects, but even here there was an increase in the use of non-copyleft licenses in 2010.

This last chart illustrates something significant about the previous dominance of strong copyleft licenses: that it was achieved and maintained to a significant degree due to the vendor-led open source projects, rather than community-led projects.

One of the main findings of our Control and Community report was the ongoing shift away from projects controlled by a single vendor and back toward community and collaboration. While some might expect that to mean increased adoption of strong copyleft licenses – given that they are associated with collaborative development projects such as GNU and the Linux kernel – the charts above indicate a shift towards non copyleft.

As previously noted, while free software projects utilize strong copyleft to ensure that the software in question remains open (or as Bradley M Kuhn recently put it, to keep developers “honest”), vendors using the open core licensing strategy use strong copyleft licenses, along with copyright ownership, to ensure that only they have the opportunity to take it closed.

Either way, strong copyleft is used as a means of control on the code and the project, and our analysis backs up Ian’s contention that there is a trend away from control and towards more permissive non-copyleft licenses.

This is part of what we called the fourth stage of commercial open source business strategies and is being driven by the increased engagement of previously closed-source vendors with open source projects.

The fourth stage is about balancing the ability to create closed source derivatives with collaborative development through multi-vendor open source projects and permissive licensing, and as such it not only avoids the need to control a project through licensing, it actively discourages control through licensing.

That is why, in my opinion, the decline of the copyleft licenses has only just begun.

*The method is not perfect, since it plots the license being used today against the year of formation, and as such does not reflect licensing changes in the interim. It does provide us with an overview of general historical trends, however.

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#1 Bradley M. Kuhn on 06.06.11 at 11:10 am

Please note that despite many inquiries that I’ve made to Black Duck, they absolutely refuse to publish their methodology and mechanisms for producing these “findings”. This isn’t a scientific study, it’s just Black Duck marketing materials. The material should be therefore ignored by serious researchers in my opinion.

I’ll note that Google’s similar analysis, which actually is more favorable for GPL, suffers from similar problems unfortunately.

AFAICT, FLOSSMole is the only project attempting to generate this kind of data and analysis thereof in a scientifically verifiable way.

#2 Matthew Aslett on 06.06.11 at 11:14 am

Well, they told me “The license usage data represents all the OSS projects we’ve spidered and have in our Knowledgebase which is now around 500,000.”

Either way, I’m not sure ignoring the findings is particularly useful.

#3 Bradley M. Kuhn on 06.06.11 at 11:18 am

Matthew, I wonder: If a consortium of mobile phone manufacturers came out with a study that said there are no health impacts of using mobile phones, but refused to give any information about how the study was conducted, what scientific methodologies were used, or anything like that, would you report it as scientific fact, or ignore the study? If you don’t answer that you’d do the former, then I don’t see how you can report Black Ducks “findings” as facts as you do above.

#4 Hen on 06.06.11 at 11:38 am

This is more like the manufacturers saying there is a health problem.

It’s in Black Duck’s interest to have GPL grow, not shrink. More GPL = more concern when buying companies, products and releasing your own products that the code isn’t worth what you think its worth. If everything was permissive then they’d get a lot less money.

#5 Matthew Aslett on 06.06.11 at 11:50 am

The comparison doesn’t make sense – unless you know something about Black Duck that I don’t.

#6 Hen on 06.07.11 at 3:21 am

I take Bradley’s example to be that you wouldn’t trust cellphone companies to publish a report in their favour. In this case however BD’s business would be better served by inflating the GPL numbers – lending (some) more credibility to the figures.

#7 Matthew Aslett on 06.06.11 at 2:56 pm

A better comparison might be election polling results. Do you ignore a poll result unless you know precisely who was polled, when and how, or do you take it as an indicator (probably one of several/many) of a potential outcome? An incumbent that chooses to ignore any poll that shows a steady decline in their their popularity does so at their own risk

#8 What to do if adoption of copyleft licenses declines | ][ stefano maffulli on 06.06.11 at 12:22 pm

[…] adoption of copyleft licenses really declining? Blackduck Sotware with its own secret recipe says so, as Matt Aslett reports. Whether or not this is true we can’t tell because BlackDuck […]

#9 Jack Repenning on 06.06.11 at 1:00 pm

Your analysis of the patterns agrees with my impressions over the last few years, but I’d phrase it somewhat differently: rather to most folks’ surprise, the invasion of commercially-sponsored open-source projects was a major shot in the arm for the GPL. The CopyLeft “IP jiu jitsu” has been as powerful a weapon for commercial interests as for freedom.

But if that’s the way of it, then the decline of GPL due to contraction of commercial open source will probably be limited, declining to the historic communitarian balance.

#10 Matthew Aslett on 06.06.11 at 1:11 pm

Hi Jack, Yes, good point, what we’re seeing is probably more of a re-balancing than a terminal decline. While I stated that “the decline of the copyleft licenses has only just begun” my guess is that it will also level off over time.

#11 Christian Schaller on 06.06.11 at 1:12 pm

Matthew I think Bradley M. Kuhn got a point, it is not about whether Black Duck got ulterior motives or not, it is just about being clear that using commercial data that you have no way of verifying is at best an indication, not undisputable proof. The problem is that when you leave behind the world of verifiable data you quickly end up in the world of ‘everyone knows’, which basically means hearsay and random anecdotes.

#12 Matthew Aslett on 06.06.11 at 1:20 pm

Fair enough. I never claimed it was indisputable, I merely raised it as evidence. Likewise no one has to believe our data either.

#13 Популярность копилефт-лицензий падает | – Всероссийский портал о UNIX-системах on 06.06.11 at 10:19 pm

[…] Согласно сводке результатов исследований, проведённых экспертами центра Open Source Resource Center компании Black Duck процентное количество отрытых проектов, использующих лицензии семейства GPL, снизилось с 70% (июнь 2008 г.) до 61% (июнь 2011 г.), а использование конкретно лицензии GPLv2 снизилось с 58% до 45% за те же три года. При этом количество проектов, использующих GPL-лицензии, в реальном исчислении увеличилось за последние несколько лет. Например, число проектов под лицензией GPLv2 возросло на 5.5% между июнем 2009 и июнем 2011 года, в то время как общее число проектов с отрытым кодом увеличилось более чем на 16%. […]

#14 Atrawog on 06.07.11 at 6:36 am

I think what we are seeing is that companies and individualist are starting to choose different types of licenses. BSD & Apache licenses have become quite popular for companies and startups, because they give more freedom on when to release code. While GPL type of licenses are still the number one for projects which are started by hobbyist.

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#16 Grigor on 06.07.11 at 8:23 pm

I’d think that there is a balance between copyleft and non-copyleft licenses. Non-copyleft generally allows more freedom, but also more freeriding. When the freeriding becomes too popular, a shift towards copyleft begins; when FR falls below a certain degree, the shift changes direction. The license inertia (typically a project license can’t be changed overnight), the perception inertia and the different tolerance of different developers towards the FR make the process less predictable, but I believe it is the strongest trend maker in the CL/non-CL licenses ratio.

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#32 Theodore R. Smith on 12.16.11 at 11:27 am

Whenever I want to make something, I refuse to be infected by viral licenses, such as the GPL ones.

If you have a library I want and you use the GPL 2, forget it. APL or GPL3? I will feel *better* dissing your project. LGPL, *maybe*.

But if I see you using the GPL or APL *AND* suing devs (individuals or corporations, doesn’t matter) for using your stuff without your royal permission (Drupal, WordPress, Calibre, and Joomla, I’m looking at you!), I *will* stop using your product and as a software engineer, attempt to offer a BSDL/MIT/Apache licensed project in its place.

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#38 Quora on 06.03.12 at 10:55 pm

Why do companies such as Google and Facebook mostly release their open source code under the Apache license? Aren’t BSD or MIT better alternatives?…

The short answer to your question is legal niceties. While any open source licensing decision should be backed by a reasonable business strategy, if your goal is widespread adoption, then a permissive license makes the best choice usually. If you want …

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