Vitalik Buterin, co-founder of Ethereum, said he is rethinking his longstanding preference for tolerant software licensing by advocating for a wider use of the “copyleft” framework, which enters what open source has described as a more competitive and concentrated era.
In a blog post published on July 7th, Buterin explained that acceptable licenses such as MIT and CC0 were historically his choice as they could encourage wider adoption, as they could be used, modified and redistributed by anyone with minimal restrictions.
In contrast, CopyLeft licenses such as GPL and CC-by-SA require that derivative work be shared under the same terms, including publishing the source code.
Butarin wrote:
“Historically, I’ve been a fan of a tolerant approach, and more recently I’ve been warmed by the copyleft approach.”
Ethereum co-founders have become much more active in recent months, proposing new ideas and conducting research amid changing priorities.
Protects openness
Buterin said his previous preferences stem from two core beliefs. The first said that generous licensing reduced friction among companies that hesitate to share their work, and reduced philosophical opposition to second copyright and intellectual property law.
He said that tolerant licensing is the closest practical approach of “no copyright at all” and is consistent with his belief that sharing data and ideas should not be considered theft.
But he is now looking at three major factors that are changing this calculation. The first is that open source has become the mainstream industry-wide, not only used by companies like Google, Microsoft, Huawei, and other, but also publish important projects under open licenses.
In this environment, copyleft requirements are not barriers, and they can be proactively open to ensuring that large companies can share improvements with their communities.
The second factor is the cultural change within the crypto industry itself. Buterin has increasingly described the space as “competitive mercenaries,” and there are fewer projects that open-source purely code from ideology and goodwill.
In this context, he argued that acceptable licenses alone are not sufficient and that legal requirements based on copyleft are necessary to ensure sharing progress.
Focused global economic debate
The third factor driving Buterin’s shift is rooted in economic theory. Using an idea from Radical Markets Economist Glen Weyl, he argued that strict property rights lead to concentration of power in an industry that goes back to hyperlinear scale.
He explained that if one actor has twice the resources of another and can produce more than twice the output, the gap will produce compounds over time, resulting in monopoly.
Buterin warned that these conditions, combined with rapid technological advancements and geopolitical instability, are threatening to create a sustained, self-reinforced power imbalance between businesses and countries.
He said some governments are responding with policies to implement technology spread, including the EU’s standardization mandate, China’s technology transfer regulations and the recent ban on US non-competitive agreements.
Buterin argued that Copyleft achieves similar diffusion goals in a neutral and decentralized way, without endorsing a particular actor or demanding top-down enforcement, and describes them as “a broad and neutral way of promoting diffusion.”
He said:
“CopyLeft creates a large pool of code (or other creative products) that can only be legally used if you are willing to share the source code of what you build on it.”
Buterin acknowledged that generous licensing still makes sense when universal adoption is a primary goal and a valuable component of property rights.
However, he urged developers to recognize that copyleft’s benefits are “a lot bigger than it was 15 years ago,” and urged that the open source community should seriously consider the mechanisms that prevent copyleft from excessive power concentration and make technological advances accessible to everyone.
His comments are because the AI and blockchain development communities are actively discussing licensing models amid concerns that there is a risk that fundamental innovation is being captured by small groups of dominant players.