FOSS idea how to go about keeping it that way?

FOSS = Free Open Source Software

I have an idea for an app that I think would be useful for any HA user. I don’t want to go threw patent bs etc. It is very simple and obvious. It would cost almost nothing. Unlike existing solutions. I want any company to be free to use it and not need to charge us a bunch for it.

Any idea how to go about this?