The Circle of Fifths
An interactive, playable circle of fifths, all 15 key signatures engraved in real notation, with playable scales and diatonic chords, and correct enharmonic spelling. One HTML file, no build step.
Daniel Jensen · djen.dev
I’m a developer and musician at Brigham Young University. I make interactive music theory tools, harmony-analysis software, and practice companions, plus the occasional utility that has nothing to do with music at all.
About
I’m a developer figuring out AI, an experienced language learner, and a classically trained pianist, based in Provo, Utah, and studying at Brigham Young University. Music was my first language, and years of classical training and learning foreign languages shape how I think about patterns, practice, and getting the details right.
These days most of my energy goes into building things with AI and software, from interactive theory tools to models that learn how classical music actually moves. I’m just as happy picking apart a new language, the human kind or the programming kind, as I ever was at a keyboard.
Featured work
An interactive, playable circle of fifths, all 15 key signatures engraved in real notation, with playable scales and diatonic chords, and correct enharmonic spelling. One HTML file, no build step.
An on-device AI prompt editor for macOS, built on Apple Intelligence, to refine and manage prompts entirely on your own machine.
A study-companion Chrome extension with local PDF extraction and an extension-managed reward tab to keep focus sessions honest.
An ongoing cluster of private work: a harmony-analysis API, a tonal-harmony model I trained on a classical MIDI corpus, and NoteBuddy, a practice companion. Ask me about it.