A simple hex calculator in the browser. I made this because there's other browser hex calculators but p much all have ads, look ugly, and who knows what they do with the values you input.
Just clone this and open the file in your browser. Or just deploy it on your own host. Demo here: https://n0.lol/hc/
Big feature is that it keeps track of whatever calculations you do as long as you don't refresh the window.