u/Pentania

Hi everyone,

I've been a musician for as long as I can remember, and it took me a very long time to really understand the relationship between chord progressions and the scales that can be used over them. Honestly, it's still something I work on every day, and I probably will for the rest of my life

Along the way, I built a small tool for myself that combines ideas from music cognition research (particularly the work of Krumhansl and Kessler) to identify keys and harmonic structures in complex chord progressions (especially extended chords with four or more notes)

What sounded simple at first turned out to be anything but. Getting reliable harmonic analysis required a lot of fine-tuning, testing against real musical examples, and many iterations before I felt comfortable calling the engine 'serious'

The result is a tool where you can enter a chord progression and get:

-The most likely key or keys

-Harmonic structures (II V I progressions, turnarounds, cadences, etc..)

-Scale suggestions based on either the harmonic context or individual chords with the fretboard diagram in all key

Once the harmonic analysis engine was working well, I also added more than 50 scales, including Harmonic Major, Double Harmonic, and several less common ones.

If you'd like to try it, it's available at: https://pentania.com
(you can load jazz standard or write your own chord chart with "new chart" button)

And if not, that's completely fine too.

Transparency note: yes, AI was involved. No, this wasn't a "prompt => app" project. The harmonic analysis engine was built manually and took more than a month of iteration, testing, and fixing all the ways real-world chord progressions refuse to behave nicely.

Hey everyone

This started as an ugly tool I built for myself. You know the moment: you're staring at a chart thinking "ok, nice changes… but what do I actually play over this Cm7b5?" and I got tired of working it out by hand every time. So I hacked something together. It was held together with tape, but it worked, and at some point I figured it might actually help other people too. So I cleaned it up

It's free, no signup, you can just open it and paste a tune

The idea is that it reads the song instead of looking at chords one by one: it finds the key, the ii-V-I's, secondary dominants, tritone subs, modal vamps. Then it suggests a scale per chord, with the guide tones, the notes to avoid, and the why. There's a beginner mode (one scale per section, so you're not drowning) and a deeper mode if you want to dig. It shows the scale on piano + fretboard and loops the changes at any tempo, straight or swing, right on your phone. Honestly it works fine for a total beginner, or for anyone who just wants to mess around and experiment

try it: https://pentania.com

What I'd genuinely love to know:

• Does the analysis match how you'd think about these tunes?
• Where does it get it wrong? (this is the big one, feed it your nastiest chart)
• Is "a scale per chord" even the right way to frame it?
• Anything confusing or ugly in the UI?

I'm a solo dev and musician doing this on the side. I'm not trying to get rich, if it ever pays for its hosting and a new set of strings, I'll be a happy man! (There's a small paid tier for the deep stuff, but the whole analysis is free)

Brutal honesty welcome. Thanks for reading

Body is walnut/plane tree.

Hardtail

Hot noiseless

Please fender, do not sue me ahahah