As many have said, IANAL but I’ll give my 2¢ as well. Your options are probably going to come down to your employment contract and where the company is based ou

As many have said, IANAL but I’ll give my 2¢ as well. Your options are probably going to come down to your employment contract and where the company is based out of. Possibly even where you live. My non-lawyer understanding is that if you live in California and your company is based or the contract states that it is intended to be interpreted by California law then I’ve always operated under the following understanding: (Not a lawyer but...) I’ve been led to believe you are safe if you work on your own time, with your own resources and it does not directly relate to the employer. I think someone referred to this once as The California Clause. If that is the right name then I’d say the California clause is not going to protect your ownership on this case. However, maybe you aren’t in California? It is hard to imagine a state in the US that is more employee friendly so I would be surprised if you found your situation better elsewhere. Besides possibly another country? Even then I’d be surprised. Things tend to trend the other direction outside of California. That being said, many have told you to discuss with a lawyer. And some have even warned that it can cause unnecessary conflict if you do. They aren’t wrong but you can always talk to a lawyer just to see what they think your options are. If this is as much of a slam dunk case in favor of your employer as I assume it is, I like to think a good lawyer would be able to let you know. On the bright side, if your employer does take it over and they still allow it to be open source, that’s super great! Getting paid to do open source is a blessing. There are also so many benefits to being the creator of a valuable tool in your company. These things can often lead to promotions, bonuses and all kinds of personal fulfillment at work. If you do learn that you’re going to have to hand it over, find a way to spin it into a good thing. Don’t let it make you bitter. And next time you build something on the side, consider your employment contract and decide if you want to build something that doesn’t relate with your employer so you might have a better shot to align your desire to keep it. Try not to let this make you bitter. This could be a great thing whichever way it turns out.