The website
The website is built up using very basic HTML and CSS, it is the JavaScript that is interesting on this website. You can input chords in the input fields, and when you press the buttons +1/-1, the chords get transposed. So if you press the “+1”-button, a G# becomes A, for example. I have of course labeled the buttons so you know which will transpose up the the original key, and which one you use when you want to know where to put the capo. When you have found chords you can play, you simply read what the number says between the buttons.
Capo Transposer