Built a small tool to check flip profit after fees — looking for feedback

I’ve been flipping items on and off and got tired of trying to mentally calculate profit after marketplace fees. So I made a small tool for myself called FlipCheck.

You can enter the buy price, expected sale price, and marketplace and it calculates:

estimated profit after fees

ROI

break-even price

a simple flip rating

I’m not selling anything — it’s just something I built and I’m trying to improve it.

If anyone here flips regularly, I’d love advice on:

features that would actually be useful

whether the fee estimates look accurate

anything that would make the tool better

If anyone wants to try it and give feedback: