> In any case, it changed years later when a startup using Nodemailer was acquired for half a …

I get that, but the author did not try something like the BSL, just went to a fairly typical proprietary license. Even the right open source license, such as the AGPL, would probably have worked well, with the proprietary license as an option (in the same way he tried LGPL + MIT).

I’ve been sitting on some code for about 15 years because it’s the key to disrupting a couple of entrenched players and would enable cloud vendors to offer the functionality “as a service”. No way I want Amazon/google/MS to run away with it. Edit down voters might ask themselves what is much older than 15 years that some companies pay a lot of money for?

This is why copyleft is necessary, and also why large companies have spread a lot of anti-GPL propaganda. In a larger sense, we desperately need a societal shift in perspective from naively viewing companies as benevolent by default, to viewing companies as they actually are by default: they'll literally kill people if it's profitable.

Not billions, but I was in a similar position. What saved me was the GPL license on the open source code and hiring a lawyer that kept my ownership of any software I wrote (though at a reduced hourly for them) and patenting new ideas connected to the project. When it came time for the company to scale up, I couldn’t have been in a better position.

More galling than the company getting acquired for half a billion dollars is the fact that they never even said "thanks"... > I searched my mailbox for emails related to that company and found a single complaint about a feature. No pull requests, no donations, no nothing.