Skip to content


It's time to say goodbye to the GPL

Published by Martin Kleppmann on 14 Apr 2021.

The trigger for this post is the reinstating of Richard Stallman, a very problematic character, to the board of the Free Software Foundation (FSF). I am appalled by this move, and join others in the call for his removal.

This occasion has caused me to reevaluate the position of the FSF in computing. It is the steward of the GNU project (a part of Linux distributions, loosely speaking), and of a family of software licenses centred around the GNU General Public License (GPL). These efforts are unfortunately tainted by Stallman’s behaviour. However, this is not what I actually want to talk about today.

In this post I argue that we should move away from the GPL and related licenses (LGPL, AGPL), for reasons that have nothing to do with Stallman, but simply because I think they have failed to achieve their purpose, and they are more trouble than they are worth.

First, brief background: the defining feature of the GPL family of licenses is the concept of copyleft, which states (roughly) that if you take some GPL-licensed code and modify it or build upon it, you must also make your modifications/extensions (known as a “derivative work”) freely available under the same license. This has the effect that the GPL’ed source code cannot be incorporated into closed-source software. At first glance, this seems like a great idea. So what is the problem?

The enemy has changed

In the 1980s and 1990s, when the GPL was written, the enemy of the free software movement was Microsoft and other companies that sold closed-source (“proprietary”) software. The GPL intended to disrupt this business model for two main reasons:

  1. Closed-source software cannot easily be modified by users; you can take it or leave it, but you cannot adapt it to your own needs. To counteract this, the GPL was designed to force companies to release the source code of their software, so that users of the software could study it, modify it, compile and use their modified version, and thus have the freedom to customise their computing devices to their needs.
  2. Moreover, GPL was motivated by a desire for fairness: if you write some software in your spare time and release it for free, it’s understandable that you don’t want others to profit from your work without giving something back to the community. Forcing derivative works to be open source ensures at least some baseline of “giving back”.

While this made sense in 1990, I think the world has changed, and closed-source software is no longer the main problem. In the 2020s, the enemy of freedom in computing is cloud software (aka software as a service/SaaS, aka web apps) – i.e. software that runs primarily on the vendor’s servers, with all your data also stored on those servers. Examples include Google Docs, Trello, Slack, Figma, Notion, and many others.

This cloud software may have a client-side component (a mobile app, or the JavaScript running in your web browser), but it only works in conjunction with the vendor’s server. And there are lots of problems with cloud software:

  • If the company providing the cloud software goes out of business or decides to discontinue a product, the software stops working, and you are locked out of the documents and data you created with that software. This is an especially common problem with software made by a startup, which may get acquired by a bigger company that has no interest in continuing to maintain the startup’s product.
  • Google and other cloud services may suddenly suspend your account with no warning and no recourse, for example if an automated system thinks you have violated its terms of service. Even if your own behaviour has been faultless, someone else may have hacked into your account and used it to send malware or phishing emails without your knowledge, triggering a terms of service violation. Thus, you could suddenly find yourself permanently locked out of every document you ever created on Google Docs or another app.
  • With software that runs on your own computer, even if the software vendor goes bust, you can continue running it forever (in a VM/emulator if it’s no longer compatible with your OS, and assuming it doesn’t need to contact a server to check for a license check). For example, the Internet Archive has a collection of over 100,000 historical software titles that you can run in an emulator inside your web browser! In contrast, if cloud software gets shut down, there is no way for you to preserve it, because you never had a copy of the server-side software, neither as source code nor in compiled form.
  • The 1990s problem of not being able to customise or extend software you use is aggravated further in cloud software. With closed-source software that runs on your own computer, at least someone could reverse-engineer the file format it uses to store its data, so that you could load it into alternative software (think pre-OOXML Microsoft Office file formats, or Photoshop files before the spec was published). With cloud software, not even that is possible, since the data is only stored in the cloud, not in files on your own computer.

If all software was free and open source, these problems would all be solved. However, making the source code available is not actually necessary to solve the problems with cloud software; even closed-source software avoids the aforementioned problems, as long as it is running on your own computer rather than the vendor’s cloud server. Note that the Internet Archive is able to keep historical software working without ever having its source code: for purposes of preservation, running the compiled machine code in an emulator is just fine. Maybe having the source code would make it a little easier, but it’s not crucial. The important thing is having a copy of the software at all.

Local-first software

My collaborators and I have previously argued for local-first software, which is a response to these problems with cloud software. Local-first software runs on your own computer, and stores its data on your local hard drive, while also retaining the convenience of cloud software, such as real-time collaboration and syncing your data across all of your devices. It is nice for local-first software to also be open source, but this is not necessary: 90% of its benefits apply equally to closed-source local-first software.

Cloud software, not closed-source software, is the real threat to software freedom, because the harm from being suddenly locked out of all of your data at the whim of a cloud provider is much greater than the harm from not being able to view and modify the source code of your software. For that reason, it is much more important and pressing that we make local-first software ubiquitous. If, in that process, we can also make more software open-source, then that would be nice, but that is less critical. Focus on the biggest and most urgent challenges first.

Copyleft software licenses are a legal tool that attempts to force more software vendors to release their source code. In particular, the AGPL is an attempt to force providers of cloud services to release the source of their server-side software. However, this hasn’t really worked: most vendors of cloud software simply refuse to use AGPL-licensed software, and either use a different implementation with a more permissive license, or re-implement the necessary functionality themselves, or buy a commercial license that comes without the copyleft clauses. I don’t think the license has caused any source code to become available that wouldn’t have been open source anyway.

As a legal tool to promote greater software freedom, I believe copyleft software licenses have largely failed, since they have done nothing to stop the rise of cloud software, and probably not done much to increase the share of software whose source is available. Open source software has become very successful, but much of this success is in projects with non-copyleft licenses (e.g. Apache, MIT, or BSD licenses), and even in the GPL-licensed projects (e.g. Linux) I am skeptical that the copyleft aspect was really an important factor in the project’s success.

I believe a much more promising legal tool to promote software freedom is in government regulation. For example, the GDPR includes a right to data portability, which means that users must be able to move their data from one service to another. Existing implementations of portability, such as Google Takeout, are quite rudimentary (what can you really do with a big zip archive of JSON files?), but we can lobby regulators to push for better portability/interoperability, e.g. requiring real-time bidirectional sync of your data between two apps by competing providers.

Another promising route I see is pushing public-sector procurement to prefer open source, local-first software over closed-source cloud software. This creates a positive incentive for businesses to develop and maintain high-quality open source software, in a way that copyleft clauses do not.

You might argue that a software license is something that an individual developer can control, whereas governmental regulation and public policy is a much bigger issue outside of any one individual’s power. Yes, but how much impact can you really have by choosing a software license? Anyone who doesn’t like your license can simply choose not to use your software, in which case your power is zero. Effective change comes from collective action on big issues, not from one person’s little open source side project choosing one license over another.

Other problems with GPL-family licenses

You can force a company to make their source code of a GPL-derived software project available, but you cannot force them to be good citizens of the open source community (e.g. continuing to maintain the features they have added, fixing bugs, helping other contributors, providing good documentation, participating in project governance). What worth is source code that is just “thrown over the wall” without genuine engagement in the open source project? At best it’s worthless, and at worst it’s harmful because it shifts the burden of maintenance to other contributors of the project.

We need people to be good contributors to the open source community, and this is achieved by setting up the right incentives and by being welcoming, not by software licenses.

Finally, a practical problem of GPL-family licenses is their incompatibility with other widely-used licenses, making it difficult to use certain combinations of libraries in the same project and unnecessarily fragmenting the open source ecosystem. Maybe it would be worth putting up with this problem if the GPL had other strong advantages, but as I have explained, I don’t think those advantages exist.

Conclusion

The GPL and other copyleft licenses are not bad; I just think they’re pointless. They have practical problems, and they are tainted by the behaviour of the FSF, but most importantly, I do not believe they have been an effective contributor to software freedom. The only real use for copyleft nowadays is by commercial software vendors (MongoDB, Elastic) who want to stop Amazon from providing their software as a service – which is fine, but it’s motivated purely by business concerns, not by software freedom.

Open source software has been tremendously successful, and it has come a long way since the origins of the free software movement born from 1990s anti-Microsoft sentiment. I will acknowledge that the FSF was instrumental in getting this all started. However, 30 years on, the ecosystem has changed, but the FSF has failed to keep up, and has become more and more out of touch. It has failed to establish a coherent response to cloud software and other recent threats to software freedom, and it just continues to rehash tired old arguments from decades ago. Now, by reinstating Stallman and dismissing the concerns about him, the FSF is actively harming the cause of free software. We must distance ourselves from the FSF and their worldview.

For all these reasons, I think it no longer makes sense to cling on to the GPL and copyleft. Let them go. Instead, I would encourage you to adopt a permissive license for your projects (e.g. MIT, BSD, Apache 2.0), and then focus your energies on the things that will really make a difference to software freedom: counteracting the monopolising effects of cloud software, developing sustainable business models that allow open source software to thrive, and pushing for regulation that prioritises the interests of software users over the interests of vendors.

Thank you to Rob McQueen for feedback on a draft of this post.