RNG Chords

RNG Chords is a browser-based random chord generator for guitarists, pianists, songwriters, and producers.

Dice pick the chords, the browser plays them back, and MIDI export gets the idea out. Keep what works, reroll the rest.

Why it exists

Sometimes you want a fresh progression without opening a full DAW session or overthinking theory first.

RNG Chords helps you:

• Roll a first idea in seconds
• Keep the chords that feel good
• Reroll the weak spots
• Hear the result right away
• Export MIDI when the idea is worth keeping

Who it is for

• Guitarists looking for voicings outside the usual shapes
• Pianists who want color without menu-diving through plugins
• Songwriters stuck on a verse, a chorus, or a bridge
• Producers sketching harmony before they arrange anything

What it does

• Roll guided or advanced chord progressions
• Preview single chords and play full ideas in the browser
• Switch between multiple playback instruments
• Keep or reroll individual chords
• Save idea snapshots into A, B, and C slots
• Restore your last creative session after refresh
• Change rhythm feel without rebuilding the whole progression
• Toggle lightweight theory labels
• Build chords manually or paste typed chord symbols
• Export ideas as MIDI

Example outcomes

Depending on complexity and tempo, a roll can land anywhere from a bright indie-pop lift to a slower neo-soul drift to something darker with more tension in it.

Tech stack

• Astro
• React
• Motion
• Tone.js
• Bun

Getting started

Install dependencies:

bun install

Start the dev server:

bun run dev

Build for production:

bun run build

Run the full check suite:

bun run lint && bun run typecheck && bun test

Start fast

• Pick an instrument focus that matches how you play
• Choose Easy, Color, or Tension chord complexity
• Click Roll New Idea or Surprise Me

Roll ideas

• Use Roll New Idea or Roll This Setup depending on where you are in the app
• Use Surprise Me to randomize the musical setup and playback instrument

Shape the progression

• Use Keep to pin a chord you like
• Use Reroll on a single slot for a fresh replacement
• Use Reroll Unlocked to refresh only the chords you did not keep

Compare versions

• Save the current idea into slot A, B, or C
• Click a filled slot to load that saved version back in

Play and preview

• Pick an instrument and tempo in the playback panel
• Change the rhythm Feel to reshape playback phrasing
• Use Play, Stop, and Loop to audition ideas
• Use Export MIDI when you want to continue elsewhere

Manual input

• Use the manual builder if you already hear a chord shape in your head
• Paste typed chord symbols like Cmaj7, Am7, D7, Gmaj7
• Mix manual input with rolled ideas when you want a more directed progression

Keyboard shortcuts

• Space: play or stop
• ← / →: preview neighboring chords
• Enter: replay the selected chord preview

Project structure

/
├── docs/
├── public/
├── src/
│   ├── components/
│   ├── lib/
│   ├── pages/
│   └── styles/
├── tests/
└── package.json

Notes

• The app is built for sketching, so most of the theory decisions stay with you
• Playback uses browser audio, so the first interaction may need to unlock audio on some browsers
• Social sharing metadata becomes fully absolute when SITE_URL is set for production