Dear Rich: Who owns the rights to software that is developed voluntarily and during one's own free time (after work hours) but who offers use of the software to his employer? I'm so glad you asked. As a general rule, if the software is not something you would create in the course of your employment and you created it on your own time, using your own equipment, then you own it. If you let your employer use it, then you have granted a non-exclusive implied license. To get a more comprehensive answer, the Dear Rich staff would need to know:
Did you create the software at work (or using work equipment)?
Does the software use code or trade secrets owned by or developed for your employer?
Does your employee handbook at work have rules regarding employee-created innovations?
If the answers are all, "No," then you own the rights. If you answered "Yes" to some or all of the questions, you may still own the rights but you will need to sort out some murkier issues. You can find an explanation for all these principles in my book, Profit From Your Idea. (Try searching inside the book using Google Book Search). Keep in mind that even if your employer owned the rights, you might still be able to earn revenue from the software.