I was assembling a custom string set for my guitar, and for that I needed to calculate the tensions of the string gauges, according to the scale length. Although I found a couple string tension calculators online, pretty much all of them had terrible usability. So I decided to write my own string tension calculator, with the best usability I could think of as an user.
It’s hosted on GitHub Pages: https://rodrigocfd.github.io/string-tension-calc/
I also made it open source on my GitHub account, and I hope to make further improvements.