Free coding is a thing!
Pretty cool! I also have been working on some tools during the quarantine. It’s called fretful, it’s intended to be a public npm Vue package to be used by other developers in their projects. It can be used in multiple contexts, including music courses and chord charts. I’ll consider doing a React version also. Eventually, I’d like to have a demo page which any stringed instrument player can use to study note names, scales, chords, etc.
You can check the WiP at fretful.netlify.app