I told my boss I had an idea for a program that could improve efficiency across much of the business, and he let me build it on company time. In the long term, he wanted to be able to sell it to other companies. However, the program never got implemented due to personnel mismanagement, and I’d rather be able to post it on my github under a free licence so I can use it as a resume item, and at least someone would have the chance to actually use it. It’s all still in my head, and I could write it again if I wanted. If I do, is it illegal to publish it? What if I write it in a different language? Do I need to change the variable names? I did plenty of research and planning on company time to build it, and it’s not like I can research it again, it’s all still in my head.
I dealt with a similar situation by simply purchasing the code from my employer. I guess that technically it was a form of licensing, because we both had the right to use, modify, and resell as we saw fit as long as there were no infringements on branding or trademarks.
They may not offer favourable terms, but it might be worth asking.