Why I used to prefer permissive licenses and now favor copyleft

Why I used to prefer permissive licenses and now favor copyleft

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

I'm still in favor of permissive:

1. Not all copyleft licenses are compatible between them. So, you may be able to use A||B but not A&&B.

2. Downstream from #1, you end up seeking legal assistance in order to build the thing you want to build and understand what is the proper license you have to use for the result using A&&B.

3. Permissive made much more sense when we actually distributed software. When it's all about services, it doesn't matter, does it?

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In the 90s I used to be a GPL fanatic. GPL was practically all we had, Linux was the thing of the day, everything was GPL in Linux and life was easy.  But then we realized GPL was not suitable to then modern needs, and we got GPLv3, and Mozilla, and Apache, and AGPL, etc. 

And it seems to me that this is often just a theater. 99% of devs, open source devs, that believe in the power of open code, have no idea what these licenses are. They have no idea if they are using them correctly. And they are probably vulnerable, if their work were to be scrutinized legally. And the actual entities that could be a threat, are free to dual license, or create new licenses that align with their own specific interests.

I like BSD and MIT, because they are simple and clear.

This is an interesting, 14-years old article on the topic.

I had my GPL eta, then BSD and MIT, but for the past decade or so everything of mine has been Apache 2, my interpretation of which is "do whatever you want with the code, except file patents". Mostly to protect the code from my own employers, since that can happen sometimes.

In a world where an LLM can instantly clean room reimplement any code it sees, I think most open licences are basically the same when it comes to code sharing. Patent trolls are still a concern though.

In the 90s I used to be a GPL fanatic. GPL was practically all we had, Linux was the thing of the day, everything was GPL in Linux and life was easy.  But then we realized GPL was not suitable to then modern needs, and we got GPLv3, and Mozilla, and Apache, and AGPL, etc. 

And it seems to me that this is often just a theater. 99% of devs, open source devs, that believe in the power of open code, have no idea what these licenses are. They have no idea if they are using them correctly. And they are probably vulnerable, if their work were to be scrutinized legally. And the actual entities that could be a threat, are free to dual license, or create new licenses that align with their own specific interests.

I like BSD and MIT, because they are simple and clear.

This is an interesting, 14-years old article on the topic.

https://lucumr.pocoo.org/2013/7/23/licensing/

> 3. Permissive made much more sense when we actually distributed software. When it's all about services, it doesn't matter, does it?

AGPL requires derivative works to publish source code even if they only make the work available as a SaaS