I used to prefer permissive licenses and now favor copyleft

https://vitalik.eth.limo/general/2025/07/07/copyleft.html

by bpierre • 1 year ago

134 137 1 year ago

vitalik.eth.limo

Crypto bros rediscovering RMS 50 years later.

I primarily care about individual users and developers of my stuff, not "the society" and as such make it easy for them to use my code in any project, even closed source commercial one. The exception is 3D models where I don't anticipate commercial uses and if there are I want them to talk to me and maybe pay me some money, so sharealike it is.

Liftyee• 1 year ago

Interesting arguments in favour of technology transfer/diffusion that I really needed. However, I wonder if letting greater economies of scale form would accelerate progress overall when those economies of scale are applied to research.

Fundamentally, I think the best companies have a symbiotic (or at least respectful) relationship with their customers and not an adversarial one.

fsflover2• 1 year ago

I think the best companies have a symbiotic (or at least respectful) relationship with their customers and not an adversarial one.

What are examples of large companies like this?

vladms2• 1 year ago

Tech companies that I use and (more importantly) I pay for and I think there is a "respectful" relationship: Google (via Android), Microsoft (via office365), OVH (via servers), Proton (via email). And there are others, but tried to select known ones.

Do I like all that they do? Definitely not. But the services for which I ended up paying are reasonable. I would not like to build my one OS for a mobile, install the 10s applications required in an enterprise or manage my own data center/mail server.

Of course there are some that I find adversarial, but that is more a personal feeling - like Apple which asked X times more in price for minor (in my view) better quality for their devices.

o11c4• 1 year ago

we are not able to opt out of diffusion of progress. People move between companies and between countries and take their ideas and talents with them.

Never forget that Industry itself came to America by way of direct theft. https://en.wikipedia.org/wiki/Samuel_Slater

=====

If you care about your users, you should always prefer some copyleft license.

Prefer permissive licenses only if you want to subsidize big business. Hopefully you have a plan for when they decide to take it closed-source and outcompete you. You probably don't, though, since that's not mentioned in the aggressive "use permissive licenses" marketing campaign they've been running for the last decade or two.

Permissive licenses can fit in a niche for software that has already been implemented many times. But the downsides remain, and why aren't you just using the existing code directly? The main occasion on which I will consider it is when everybody else is doing it wrong (and content to do so), and I as a user keep getting annoyed at hitting those limitations.

The second-worst reason to use permissive licensing is arguably "I don't understand how to dynamic linking".

jjcob5• 1 year ago

Permissive licenses enable small or individual developers (like myself) to sell software based on them.

With copyleft licenses, developers always have to sell stuff adjacent to the software (support, individual development, software-as-a-service).

With permissive licenses, developers can just sell a license to the software itself. Much easier, much more direct.

It's the reason why there is much more tooling around permissive licensed projects vs. projects with a GPL style license.

Permissive licenses are win-win: Proprietory developers win because they get to sell licenses, users win because they have more tools they can use.

o11c4• 1 year ago

That does not follow. You might as well make it "source available" and sell proprietary licenses.

sampullman• 1 year ago

I'm not completely familiar with the details and haven't done it myself, but what's stopping you from selling non-restrictive licenses to a GPL project? Can't you just etch out an exception for each customer?

MangoToupe4• 1 year ago

I just don't really want to support the sale of any software. I see it as directly harmful compared to subsidizing the development of modifiable, free software, which is the true allure of computation.

tmtvl• 1 year ago

Users lose because the tools with the most functionality, the applications with the most interoperability, the software with the most mindshare,... will be proprietary software.

sparkie8• 1 year ago

There are alternatives. We can dual license software under a strong copyleft and a proprietary license, so that users (developers) who don't want their derived software to be copyleft can pay the proprietary license fee. IMO this is the approach that everyone should be taking - it rewards the developer rather than them subsidizing your derived works with their free time.

Obviously this has constraints. The developer must have full rights or ownership to redistribute the work under other licenses. This can be obtained from contributors via agreement, where every developer retains ownership of code they write, but grants permission to relicense it for the benefit the project. Ideally, contributors would also be rewarded for their time via bounty systems, contracts or direct employment.

It's possible to make non-derived works which utilize copyleft software. The license's conditions apply only to the derived works, and not directly to your code unless it unquestionably a derived work such as a fork. If your application is written in a way that it can function without dependency on a copyleft software, but can be augmented using copyleft software using a plugin system, then you're able to distribute your software under any license you chose, and only the plugin which uses the copyleft software would be required to be licensed under a compatible license. The "aggregate" would need to be distributed under the copyleft license - but there are also ways around that - simply distribute your software without the dependency on the copyleft work, and have it optionally download the copyleft plugins separately so that they're not part of the "aggregate".

Permissive licensing won't sustain itself unless the developers who depend on it start donating to the maintainers of the permissively licensed works they depend on. In some cases this happens, but mostly it's just the case that you can make money using software other people have given away and continue to maintain for free. What happens if they decide to stop maintaining it? Is your product still viable if you have to take over the task, or employ someone new to maintain it? Would it be viable if you, or your users, had to purchase a proprietary license fee for an alternative dependency?

wolvesechoes3• 1 year ago

You can sell GPL software. You can even sell GPL software under proprietary license as long as you are the copyright owner (dual-licensing).

Really, when you take time to understand real restrictions, as opposed to repeated myths, the only argument in favor of permissive license is that they help big players use free labor.

bityard3• 1 year ago

Why do you believe you can't sell copyleft software?

bigstrat2003• 1 year ago

If you care about your users, you should always prefer some copyleft license.

There is no possible way for users to be hurt by a permissive license. Even if some company were to make a closed source fork, who cares? The original is still there, still just as free as it ever was.

Prefer permissive licenses only if you want to subsidize big business. Hopefully you have a plan for when they decide to take it closed-source and outcompete you.

I prefer permissive licenses because I'm making a gift to the commons. It strikes me as hypocritical to say "I'm giving this to you, but only if you things the way I approve of". Thus, I make it completely free for all users, whatever they want to do with it. You may not see it that way, which is fine. But I'm sick of the false idea of "you're just subsidizing big business" being promulgated. That isn't true.

And why would I care if someone "outcompetes" me? My gift to society is still there to be used if people want, or not if they don't want. It doesn't diminish or harm my efforts in any way.

dedup• 1 year ago

Even if some company were to make a closed source fork, who cares?

They can add sufficiently popular functionality to said closed source fork and make the open source original a) obsolete and b) incompatible with the combined ecosystem, and thus deprive the users of a feasible free option.

MangoToupe4• 1 year ago

But I'm sick of the false idea of "you're just subsidizing big business" being promulgated. That isn't true.

All the permissively licensed code that came with my mac disagrees. This is even more true of iphone software: you can technically look at some of the code that comes with it, but you can't modify it.

o11c4• 1 year ago

As a reminder, the GPL (or any other Free Software license, by definition - it's "Freedom 0" in the list) places absolutely no restrictions on users. Its provisions only kick in for those who want to go beyond merely using the software.

0xEF• 1 year ago

I have a different take on permission license. I offer up what little code I produce under the assumption that anyone can use it for whatever, just give me credit. Why? Because it might result in an interesting collaboration on a project I like. If someone uses my existing code to accomplish something neat and sees who I am, they can reach out to me for more, which I'm open to since it would likely result in some growth for me as an amateur. I'm not particularly interested in making money since I recognize that I am nowhere near that level, yet, but creating a future opportunity seems like a good idea since I enjoy coding.

jampekka• 1 year ago

There is no possible way for users to be hurt by a permissive license. Even if some company were to make a closed source fork, who cares? The original is still there, still just as free as it ever was.

The users of the closed source fork are harmed. They are unable to use the software to the full extent (e.g. inspect, modify, fix bugs). This is what copyleft intends to protect.

Closed source reduces the software into an appliance and the user into a consumer.

lurk22• 1 year ago

Never forget that Industry itself came to America by way of direct theft.

Two other examples come to mind: John Rolf arrived at the Jamestown settlement in 1612, having purchased tobacco seeds presumed to have originated in Spain (where their export was supposedly punishable by death, though I haven’t found sources confirming that).

William de la Barre adapted the rollers used in Minneapolis wheat mills from a European design. I have seen a few sources claim this was industrial espionage wherein Barre obtained employment in the mill and sketched its design out to copy it for his employers in Minneapolis, though Wikipedia makes no mention of this.

https://en.wikipedia.org/wiki/William_de_la_Barre

The American publishing industry also got its start by refusing to recognize British copyrights; this didn’t change until 1891.

This is to say nothing of the more explicit, above-board technology transfers involved in bringing European experts in to develop the American industrial plant. Similar things are currently going on in Saudi Arabia and China, and to a lesser extent in South America and Africa.

And then you have Operation Paper Clip and the looting of the German industrial plant after World War II.

eru• 1 year ago

Never forget that Industry itself came to America by way of direct theft. https://en.wikipedia.org/wiki/Samuel_Slater

Wikipedia says:

He memorized the textile factory machinery designs as an apprentice to a pioneer in the British industry before migrating to the U.S. at the age of 21.

Doesn't sound like he stole anything? At most it's some infringement of intellectual properties. (Wikipedia says: 'He learned of the American interest in developing similar machines, and he was also aware of British law against exporting the designs.' But again, no theft.)

raxxorraxor• 1 year ago

There is another side to it. Instead of using open solutions, big business then copies the open solution to a degree that is permissable or a copyright vioaltion deniable. It can easily stomach the development costs. And in that case would outcompete you as well, as they offer service level agreements and build a consumer product around you solutions.

On the contrary, you would penalize small business, because they cannot stomach the increased developing costs. Large businesses wouldn't even notice the change.

Sure, for software exclusive businesses there were cases were a too permissive licence was counter productive for economic success.

sensen7• 1 year ago

Do you have any examples?

em-bee5• 1 year ago

Instead of using open solutions, big business then copies the open solution

i highly doubt that. sure technically they can copy it, but they could not guarantee 100% compatibility. yes, the model would work, but at least they would compete on somewhat equal footing.

what happened to redis, elastic search, mongodb etc was way worse. people switched to amazon and others because they got the original and did not have to risk issues when switching. further more, they also didn't have to risk lock in. (or at least had the impression of not risking lock-in)

in other words offering a functional copy vs taking the original (without paying for it) are two very different value propositions.

but amazon could have made the same offers using GPL software, or even AGPL. yes, it would have cost them more, but not as much more as developing their own. so the fact that they could afford to develop their own clone is not an argument for the original developer to just allow them to use their software without restrictions.

"you should just give this to me because i could afford to just clone it and put you out of business." what kind of choice is that?

small businesses can use GPL licensed software just as they can use permissible licensed software. if using GPL software hurts your business model more than spending the money to develop your own well then maybe it's the wrong model.

i'd argue that using GPL software can jumpstart your business faster than developing your own, and once you make enough money you can develop your own like everyone else who doesn't want to use GPL software. permissible licensed software doesn't provide that much of a jump-start. it also makes it easier for your competition.

and most importantly, it all happens at the expense of the original developer. why should they accommodate that?

rerdavies7• 1 year ago

The second-worst reason to use permissive licensing is arguably "I don't understand how to dynamic linking".

??! Not sure what that has to do with ANYTHING.

bheadmaster4• 1 year ago

You can use LGPL licensed-software in your proprietary software, as long as you only link to it dynamically - i.e. you provide a clear separation between your software and the LGPL software.

jaredklewis• 1 year ago

Prefer permissive licenses only if you want to subsidize big business.

Another reason to prefer permissive licenses is if you want anyone to use your project.

Most coding out there in the world is done in the service of a commercial enterprise and my experience is that companies won't use copy left projects. Companies are generally happy to use projects with permissive licenses or pay for SaaS or commercial licenses, but anything with the GPL is a non-starter.

There are a few, well known exceptions (Linux, GCC), but I can't think of any exceptions from projects started in the last 20 years.

I don't necessarily think this view is entirely rational or irrational, but I’m confident this attitude exists; companies using GPL projects are pretty rare. Anyone found differently?

xigoi2• 1 year ago

I’ll personally rather have companies not use my project than use it while restricting their users’ freedom.

Animats• 1 year ago

This is the Ethereum guy. Was something forked and made proprietary that he needs to be open source?

kwar132• 1 year ago

This comment makes no sense. Can you give a single precedent for him to have behaved that way?

jandrewrogers• 1 year ago

I just want anyone to be able to use my code. It isn’t ideological for me, I don’t care what people do with it. No one is harmed by a permissive license and I explicitly want to minimize the obligations of anyone using my code. I’d probably make most of it public domain if it wasn’t for the fact that some jurisdictions don’t recognize that concept.

I’ve written thousands of lines of copyleft code. I don’t see a practical benefit if you don’t want to obligate users of that code.

cess112• 1 year ago

"I just want anyone to be able to use my code."

Some would argue that if you want that, then you need to license it in a way that protects anyone's freedoms and disallows other ones from stepping on them.

rerdavies7• 1 year ago

Why would anyone serious argue that?

D13Fd• 1 year ago

This is ridiculous. He said he just wants anyone to be able to use his code. Licensing it copyleft will just restrict the user base.

indeyets• 1 year ago

It’s usually a question of “who are your users?”

As long as you consider developers of derived software to be your users — permissive makes most sense.

But if you consider end-users of software it’s definitely copyleft.

brnt• 1 year ago

It isn't for me either. A permissive license means it's a matter of time before somebody forks and keeps it from me and other users/developers. Copyleft ensures as many users/developers as possible have access to the code.

miloignis• 1 year ago

Maybe, I do think it really depends on the type of software/situation.

In an argument about how much someone is able to use something, I think you could argue that a copyleft license turns more people away than it would force to participate, so the overall amount of work that is freely available is less than it would have been with a permissive license. (That is, if 10% using a permissive license don't contribute back and 90% do, you end up with more contributions than if 100% of users contribute back to copyleft but you only have 50% as many users.)

I do think it's very situational though - clearly Linux being GPL has been a huge boon in forcing contributions, and I think the killer bit here is that forcing those contributions means that people are able to use their hardware that might otherwise only run proprietary operating systems. That is, it's the forcing open of something that hardware companies would otherwise keep closed.

On the other hand, I don't see any huge reason why a good regex library, for instance, shouldn't be permissive - making a regex library copyleft isn't going to force open some proprietary software, they'll just use some other (maybe worse, maybe equivalent) regex library, and you might get fewer overall contributions and end up with a worse overall available library.

kwar132• 1 year ago

I might not always agree with Vitalik but he's always a joy to read.

qalmakka4• 1 year ago

My favourite licence has always been the MPLv2. It's basically the best of both worlds, it's copyleft for your code while keeping the ability to statically link (crucial for Rust, Go and other languages that do that by default).

Sander_Marechal• 1 year ago

So, LGPL?

qalmakka4• 1 year ago

Well, no, as someone else already stated forcing people to ship object files is a PITA and it's really not feasible with languages that do codegen, templates, ... because you inevitably end up injecting copylefted code inside of your files.

I like copyleft as a way to protect my code from freeloaders, but I don't think that imposing the same view on other people is fair TBH. I want people to be able to use my code without being forced to "convert" to my creed first

wolvesechoes3• 1 year ago

You can link LGPL statically as well, though it puts more obligations (shipping object files) than MPL.

I am always amazed how many myths were created around FOSS licensing.

CJefferson• 1 year ago

That doesn't work for languages which require all the code at once just for compiling, like C++ (if any of the code involves templates), template Haskell, or Rust (at least, not without heroic efforts).

You could make sure the LGPL code only works through a C-API like interface, then you can sub-divide it off more easily, but that can be quite a bit of work.

qalmakka4• 1 year ago

Try doing that in Rust, C++ or Go. It's not only incredibly annoying, it's also often technically unfeasible due to macros/codegen/templates/generics, so you end up with ugly stuff like linking exceptions clauses and stuff that - guess what? often boil down to a worst version of the MPLv2

bgwalter• 1 year ago

Copyleft of course is of limited use since the FSF slept through the desktop to Internet service transition and now sleeps through the "AI" transition.

GPLv4 should be AGPL+no-AI if it is supposed to have any effect.

zorked• 1 year ago

It is copyright as a whole that is sleeping through the "AI" transition/robbery.

netbsdusers2• 1 year ago

Usually when I hear "robbery" it brings to mind someone stealing your phone or wallet at knife-point. Certainly not training some model on some code that involves neither violence nor depriving anyone of anything.

The concept of copyright is the fiction that information - something that can be freely modified, copied, or transmitted - is of the commodity-form, that information should be treated as if it were a single real object that were inherently scarce.

It is a fiction that exists to serve of some of the most hateful, mafia-like firms - your Disneys, UMGs, Getty Images, and the like.

So if the AI interests are powerful enough to deal that whole rotten system a serious blow, then I'm all for them.

tobias32• 1 year ago

Since AI use is based on "fair-use" how can you add a no-AI clause? Only protection I see is to not publish the code.

Diti• 1 year ago

“Fair use” is a notion related to copyright. The authors in Europe who won in cases of free software licensing violations did it on the grounds of breach of contract law.

mistercheph4• 1 year ago

GPLv4 should be AGPL+release the source code for your deployment/provisioning infrastructure, there is clear market demand for a freedom preserving license that defends against AWS, how hard could it be to craft something up that would be indigestible to them?

msgodel2• 1 year ago

g to their most recent 10-Q Barbie sales have been flat YoY so I guess they felt like they had to do something.

No thanks. Seriously please no, I do not want to see it, that stuff has negative value.

KronisLV• 1 year ago

...release the source code for your deployment/provisioning infrastructure...

SSPL works a bit similarly: https://www.mongodb.com/legal/licensing/server-side-public-l...

If you make the functionality of the Program or a modified version available to third parties as a service, you must make the Service Source Code available via network download to everyone at no charge, under the terms of this License. ...
“Service Source Code” means the Corresponding Source for the Program or the modified version, and the Corresponding Source for all programs that you use to make the Program or modified version available as a service, including, without limitation, management software, user interfaces, application program interfaces, automation software, monitoring software, backup software, storage software and hosting software, all such that a user could run an instance of the service using the Service Source Code you make available.

Not really a free software license, at least typically not considered one though.

jeroenhd2• 1 year ago

So far, lawsuits seem to be heading towards a "AI is not subject to copyright" direction, so a no-AI license doesn't seem practical.

As for the internet service industry: AGPL already covers that, I think. However, I'm not sure if AGPL has ever been tested in court (especially outside of the USA). For the EU there's the EUPL v1.2 which should be AGPL compatible.

I don't think there's much you can do to stop AI companies from stealing your code unless you go out of your way to make every method name, variable, and string template contain at least one slur or support for terrorism. That way, someone will need to explicitly rewrite the code for it to be spat back out, which is more effort than most AI bros are willing to put in.

sparkie8• 1 year ago

A clause in a license which states something like "You may not use this work for training an artificial neural network" should suffice.

If the AI developer ignores the term and trains his AI with it anyway, they would clearly be in violation of your licensing terms, and then it would be for a court to decide.

Having the term in your license would be preferential than omitting it, since it's hard for a court to rule that they're not in violation of your license when its written there plain as day. If you don't have the clause then you basically have no defence as it can easily be argued that they've followed your licensing terms, which don't prevent its use for such purpose.

roenxi• 1 year ago

It is pretty much impossible to square the FSF's mission or methods with limiting how people use GPLed software in relation to AI. The FSF should be one of the organisations carrying the banner that people are free to use GPL-ed software as they like.

INGELRII• 1 year ago

Third, Glen Weyl-style economic arguments have convinced me that, in the presence of superlinear returns to scale, the optimal policy is actually NOT Rothbard/Mises-style strict property rights. Rather, the optimal policy does involve some nonzero amount of more actively pushing projects to be more open than they otherwise would be.

(read the rest of his reasoning for this philosophical shift).

enriquto• 1 year ago

The very name "permissive" licenses is problematic, because it steers the discussion towards the point of view of software middlemen, not of users.

From the point of view of a user, a copylefted software allows the user to do more things: the license grants them permission to see and change the source code of the software, no matter how they got it. With so-called permissive software, the user may be stripped of this permission by third parties.

immibis4• 1 year ago

Another name for "permissive license" is "cuck license". Hopefully I don't have to explain the analogy.

sellmesoap• 1 year ago

I've taken Rob Landrey to heart on this subject. His argument for use of permissive licences to avoid the power struggle that crops up around bigger copyleft projects.

jmclnx• 1 year ago

I think it depends on what you do/did. Things I wrote is using the ISC

https://en.wikipedia.org/wiki/ISC_license

But anyone and their brother can develop those old utilities I created decades ago and enhanced over the years.

But if you create something very complex and provides a real benefit, then I can agree with this point. You may be better off to using the copyleft.

In anycase, you need to really need to think about the License you choose, not just use one because it is trendy now.

I used to prefer permissive licenses and now favor copyleft

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