I'm working at a decent employee, on a pretty specific IT topic.

I also have this idea for a startup I would like to build but there is no way I can do it on my day job (I dont even have programming tools on my job PC because I don't write software there). Even if I could, the idea would die as an internal project (they don't sell software to other companies)

The thing is that I would be the first user but on my dayjob, kind of scratching my own itch but at my job.

I find it unethical to "sell to my employer" so I was planning to be on a "free forever plan" and then look for other customers. also keeping a clear separation from my day job and my project work.

What do you think about this, is a bad idea? Is there anything I'm not seen and I'm gonna shoot myself in the foot?

Thanks!