Roundel
A practice tool for chord progressions, laid out as a transit map of the twelve
keys — see how they move, hear them, and drill them until they are automatic
everywhere.
The twelve keys are stations on a network. Each curriculum step is a line across
it; a day's workout is a departure that calls at the keys you have opened. That
map is how you navigate and how the lessons are built. The circle-of-fifths
wheel is still here — it is the terrain the network is drawn on — and it is
where you explore chords, neighbours and voice leading.
A progression is the real unit of harmony, not the chords in isolation: a
ii–V–I means something as a single shape, not three symbols to memorise
separately. Roundel puts that shape in front of you — on the wheel and across
the map — while the rest of it makes sure you can also hear it, recognise it on
your own instrument, and find it again next week.
The playing curriculum follows one loop, worked from every direction: take a
progression, hear it, drill it across all twelve keys, and apply it —
recognising it as you play, or playing along with a generated rhythm section.
SEE → HEAR → DRILL → APPLY
No staff notation, anywhere, ever. Not as an option, a toggle or an
advanced panel. Music is keyboard diagrams, the wheel itself, chord symbols,
scale-degree numbers, Roman numerals, intervals and colour. If you read chord
charts fluently and staves not at all, nothing here will ask you to.
Free software, AGPL licensed. Run it on your laptop, deploy it wherever you
like, change whatever you want. It is your own instance — no telemetry, and no
server anyone else controls. Invite-only accounts let a small trusted group
keep separate progress today; public registration and the paid hosted service
remain planned in ROADMAP.md.
What it does
- Play — connect a MIDI keyboard and it names what you play as you play it,
with the reasoning, on a harmonic wheel that shows why.
- Today — a workout of up to six tasks, composed fresh each morning and
finished by meeting its goals rather than by running a clock down. Pick any
key, any step or any progression to build it around; spaced repetition
schedules the review and a twelve-key ladder suggests where to go next, and
neither ever locks anything.
- Play along — a rhythm section generated from a chord chart. Walking bass,
drums, optional comping, any key, any tempo, loop any bars. Blues, rhythm
changes, cycles and public-domain standards, plus anything you type in.
- Explore — the wheel, chord neighbours, voice leading, with the notes under
your hands lighting up as you play them.
- Recipes — theory you play rather than read. A chord's recipe is its
formula: the intervals above its root, counted in half steps. A line of short
stops goes from half and whole steps through thirds and the fifth to triads
and seventh chords, each briefed in standard terms with the recipe drawn on C
before you build it on the keyboard; and a branch line goes up in fifths
until it comes back to C, then round the circle from memory both ways. Every
answer is a note played. It keeps its own record and leaves the courses and
the daily workout untouched.
- Profile — what has actually happened: hours played, chords judged, badges
won, and the twelve keys as swatches so the ones you never play are visible at
a glance. Every number traces to a row; none is an estimate, and there is no
daily streak.
Signing in for the first time opens a short tour that sets the instrument up
before it explains anything, and hands you the sustain pedal as the way through
the rest of it. No MIDI keyboard? Everything works with the on-screen one, and
the tour takes that route instead.
Before you start: browser support
Connecting a MIDI instrument needs Chrome, Edge or Firefox on a desktop.
Web MIDI does not exist in Safari — on iOS, iPadOS or macOS — and every iOS
browser is forced onto WebKit, so an iPad cannot drive the parts of this app
that listen to a keyboard. See DECISIONS.md for the detail.
Everything else works everywhere, including on a tablet: the wheel, the
play-along charts, the on-screen keyboard.
Web MIDI also requires a secure context. localhost counts; a deployed
http:// origin does not, and will disable MIDI with no error message. Serve
over HTTPS.
Stack
| Layer | Choice |
|---|
| App | SvelteKit 2 · Svelte 5 (runes) · TypeScript · Tailwind 4 |
| Build | Vite 8 · @vite-pwa/sveltekit |
| Data | Postgres 15+ · Drizzle ORM · node-postgres |
| Audio | Tone.js — ear drills and backing tracks only |
| MIDI | Web MIDI API |
| Deploy | adapter-auto — Vercel, Netlify, Cloudflare, or Node |
| Tests | Vitest |
Your instrument makes its own sound, so the app never synthesises a piano voice
for what you play. It only generates audio for ear drills, backing tracks and
the metronome — which is why there are no sampled instruments to vendor and the
whole thing is a few hundred kilobytes.
Running it locally
You need Node 22+ and a Postgres 15+. Docker gives you the second one.
git clone https://github.com/bparticle/roundel.git
cd roundel
npm install
cp .env.example .env # the defaults already match docker-compose
npm run db:up # start Postgres in Docker
npm run db:migrate # apply the schema
npm run db:seed # skills and chord charts
npm run account:create -- owner "Your name" "[email protected]"
npm run dev
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