License Zero [https://licensezero.com] is working on a means of doing this. I believe they are starting with NPM modules first.

> starting with NPM modules first.

Creators of left-pad about to become millionaires off the backs of lazy devs everywhere.

> I wonder if this could be done via licensing, i.e a commercial license that only kicks in when you offer the project as a service.

The AGPL can be used this way. The project is free and open source, but people wanting to sell it as a service will pay for a commercial license instead of using the AGPL.

Only if they want to modify it and not give back. If people want to use the code as is AGPL doesn't really help.

And from the outside, it's nigh impossible to know if the source code for a hosted open-source product has been modified or not, unless they make it blatantly obvious, which makes the AGPL extremely difficult to enforce. In addition, a lot of great hosted open-source products are designed to be extensible through plugin architectures so that its functionality can be extended through code that lives outside of the core codebase, and AGPL can introduce a perverse incentive to close off the product for extension to the detriment of the quality of the code base and the experience of end-users, in the name of not circumventing the protections provided by AGPL.

That said, AGPL is still my go-to license to reach for when I build open-source products that can be self-hosted, but it's by no means a silver bullet, even for its intended purpose.

People understand what the AGPL requires. And for projects where there are alternatives with other license terms, like MIT or Apache2, the alternatives will be used. Adoption is stymied