I really, really want something like this that is truly multiple platform and local. Linux and Windows are a must. Must be 100% offline so that it is useable wi

I really, really want something like this that is truly multiple platform and local. Linux and Windows are a must. Must be 100% offline so that it is useable without Internet. I'd gladly pay $60 per each major version per year. Add permissive open source license and you have me as a customer for life. Maybe I should just build it myself if others are interested?