Music Theory Trainer is a free practice site for the fundamentals of Western music theory: chords, scales, key signatures, intervals, and note reading across the staff, piano, and guitar. Built around the idea that fluency in theory comes from drilling, not memorising — every reference page links into a trainer where you can practise the thing you just read about.
Who I am
Hey — I'm Pierce. I'm a self-taught musician with no formal training. I studied music briefly in high school and now study privately with a teacher as an adult, but most of what I know I taught myself. For a stretch I was posting short YouTube explainers about music theory; one of them about the circle of fifths is embedded in the explainer article on this site.
I make music as Pierce Engineer (solo) and as one half of Bill Cole Collision (a duo with my friend). My day job is in advertising, which is unrelated to all this — Music Theory Trainer is a side project I build because I want it to exist.
Why I built this
I was working with my teacher on jazz guitar and noticed that my recall for intervals and triads was painfully slow. Every time I tried to analyse a piece or work out a lick, I'd be stuck wracking my brain trying to remember what a major sixth above F♯ was — and the cognitive load killed any chance of staying musical.
I went looking for a flashcard tool that would let me drill this stuff repeatedly until it became reflexive. Nothing I found scaled to my phone or felt right for serious practice, so I built my own. The trainers and the daily puzzle on this site are the result. They're what I personally use to keep my recall sharp.
Where it's going
The next steps I'm thinking about: more practice tools for the things you should know without thinking — so when you sit down to play, you can spend your attention on the music rather than the theory. A mobile app version (the web version already works on a phone, but offline-capable would be a real upgrade) is on the list. Also: better on-ramps for total beginners. Most of my friends who want to learn music find theory daunting, and if I can make the path less intimidating through gamification and short, focused exercises, that's a real win.
No ads, no accounts, no tracking
There are no ads on the site today. I might add some eventually if traffic gets serious — but I also like having a platform that's mine, where I can occasionally promote my own music or whatever else I think is worth pointing at. There are no user accounts, no email collection, and no analytics or tracking pixels. Your trainer progress lives in your browser; the only thing that goes to a server is your Etudle daily-puzzle result, and that's anonymous by default. Full details are on the
What's here
- Etudle — a 15-card daily puzzle with a global leaderboard, refreshing at midnight UTC.
- Practice Gauntlet — focused 5-card rounds on a random topic, no setup.
- Four trainers — Chord, Circle of Fifths, Interval, Note — with timer-based personal bests across multiple input modes (tap, music staff, piano, guitar).
- Reference pages — every chord, key, and scale explained with diagrams and links into the relevant trainer.
- Long-form guides — for the trickier topics (the circle of fifths, base triads, key signatures, major vs. minor).
Get in touch
Suggestions, bugs, requests, or anything else — DM me on Instagram at @pierce.engineer. The site is actively developed; useful feedback tends to get shipped pretty fast.