midi-chord-identifier.backwater.systems
Show HN: A real-time chord identifier web app using the Web MIDI APIhttps://midi-chord-identifier.backwater.systems/This was a quick, fun project that solves a practical problem I had — wanting to learn the names of piano chords, but not seeming to want to spend time staring at chord charts. I figured perhaps I could learn some music theory more deeply by encoding the logic into software, as well.I came across this table that breaks down the composition of chords logically. I was reminded of a bitmask, so I translated each chord into a 12–bit bitmask with a bit for each distinct note letter name (e.g. “C” or “B♭”). Decoding binary was involved in interfacing with MIDI … that might have been the inspiration — regardless, a bitmask seems ideal for this purpose.The most challenging part by far was the logic that determines whether say, “A♯/B♭” (which are considered to be the same note in the 12–tone chromatic scale) should be rendered as “A♯” or “B♭”. As best as I understand, this depends on key signature context, and the logic regarding this isn’t well-described. I settled on finding the diatonic scalFeb 17, 2026 3:52 PM
