The .NET community has just seen another open-source drama. FluentAssertions, a popular library that provides a natural and easy-to-read syntax for unit tests, has suddenly changed its license. Starting with version 8, you must pay $130 per developer if you use it in commercial projects.
Reading the related discussions on GitHub and Reddit is painful. Most people only complain about paying for something that has always been free, completely ignoring the effort the authors had to put into the library, and any constructive critique is very rare.
Every open-source project needs significant investment to ensure it will work long-term. Keeping the project healthy and reliable requires thousands of hours of its maintainers. It is perfectly OK to want to get paid for the work. The key question is how to do it without losing trust.
We saw what happened when the author of Moq published an update that collected the e-mail addresses of developers using the library. I don't think the original intent was to do any harm. Still, the idea of a library that hooks in the build pipeline, collects information from developer machines, and sends them somewhere was far behind the red line for most users.
With FluentAssertions, we can see a similar story. The NuGet package name is the same, and you may not even notice that version 8 uses a different license when upgrading. Some people reference package versions with wildcards, which upgrades the dependencies even without making a single change in the code. Yes, people can stay on version 7 forever, but the risk of accidentally upgrading the package is quite high. Don't tell me you never clicked on the "upgrade all NuGet packages in the solution" option.
I think that making such a fundamental change deserves publishing NuGet package with a different name. Also, I believe that the change was not announced early enough, and it came out as a surprise to most of the community. Whether we like it or not, paying for using open-source projects is a sensitive topic, and communicating things clearly and in advance would significantly reduce the frustration.
I still think that the only viable business model for OSS is to have an open-source core component surrounded by commercial add-ons. The core component must be free, and it must be clearly promised it will be free forever. No catches, no tricks. This is the only way to avoid losing the trust of the users. We took this strategy with DotVVM 10 years ago and I never regretted it. We managed to acquire many loyal customers over the years, and the commercial products helped the project become sustainable.
If you maintain an open-source project, I understand you need to get paid for that. I need it, too. But please be careful when transitioning to a commercial model. Every drama like this with FluentAssertions damages the overall trust in all open-source libraries.