I haven't done a quantitative study either, but here are two examples of extremely influential open source projects that the internet runs on: The spring frame

I haven't done a quantitative study either, but here are two examples of extremely influential open source projects that the internet runs on: The spring framework has contributions from many volunteers, but most big contributions and all of the integration work come from Pivotal. The contributions to the linux kernel are graphed here: https://www.extremetech.com/computing/175919-who-actually-develops-linux-the-answer-might-surprise-you https://www.extremetech.com/computing/175919-who-actually-de... 80% of new contributions are from companies. That shouldn't be surprising at all, because these companies are also the biggest users of the project. As for myself, in the rare occasions I contributed a patch to an OSS project, most of the time it was to solve a problem I encountered at work, so I have anecdotal evidence that at least some from the category 'volunteers' also got paid to write that code.