OtoTheory — Use Theory Without Tears
Build chord progressions while you listen. Swap chords, switch grooves, and shape your song in real time — no playback interruptions.
For guitar, bass, and keyboard players who want to create music with confidence.
What is OtoTheory?
OtoTheory is a chord progression builder with built-in music theory support. It works like a DJ console for songwriting: hit play, drop in chords, pick a groove, and hear your ideas come to life instantly.
Use it when you want to:
- Start a song idea from scratch
- Find chords that sound great together
- Experiment with different grooves and feels
- Get AI-powered chord suggestions while you compose
- Export your progression to a DAW via MIDI
Create music that's theoretically sound — no theory knowledge needed.
Just bring your curiosity and your instrument.
Key Features
🤖 OtoTheory AI
Get real-time chord suggestions powered by three layers of musical understanding: feel, theory, and emotion. Discover substitutions, extensions, and bridge chords — all with one tap.
🎛️ 15 Groove Patterns
Choose from 15 backing styles across five categories — Energy, Vibe, Unplugged, Traditional, and Synth. Switch grooves in real time without stopping playback.
🎸 Guitar, Bass & Keyboard Fretboard
See chord tones and scale notes on an interactive fretboard for guitar, bass, or keyboard. Two-layer overlay shows scales (outline) and chords (filled) simultaneously.
📤 MIDI Export — 3 Modes
Export your progressions in three ways: Groove (Drums, Bass, Harmony tracks), Groove + Theory (adds Scale Guide and Guide Tone reference tracks for DAW study), or Chords Only (simple whole-note chords + bass). All modes include BPM, section markers, and chord names. AirDrop to your Mac and start producing.
🎬 Section Management
Organize your song into Verse, Chorus, Bridge, and more. Customize playback order and build complete song structures before opening your DAW.
Also Included
Edit chords while the backing track plays — no interruptions.
Place two chords in one bar for ii-V moves and more.
Auto-detect the key of your progression across 8 scales.
Start from proven patterns — pop, rock, jazz, and more.
Save your work and pick up where you left off.
Browse chords by mood and feel, not just theory names.
Who is it for?
📚 Beginners
Learn which chords belong together without memorizing theory books. Hear it, feel it, understand it.
✍️ Songwriters & Composers
Sketch ideas quickly, experiment with grooves, and export MIDI to your DAW. Skip the tedious setup and jump straight into creative work.
🎓 Self-Learners
Understand practical theory through interactive visualization. No textbooks — just play along and build along.
🎸 Guitarists, Bassists & Keyboardists
Visual fretboard and keyboard overlays show exactly which notes to play. Works for guitar, bass, and keyboard.
Free vs Pro
🆓 Free (Web & iOS)
- • AI chord progression import
- • 50+ chord progression presets
- • 15 groove patterns
- • All chords (tensions, slash chords)
- • OtoTheory AI (all modes)
- • Section management
- • Fretboard visualization (guitar/bass/keyboard)
- • Key & scale detection
- • 3 local saves & text export
💎 Pro (iOS, 7-day free trial)
- • MIDI/audio export — 3 modes (unlimited)
- • Unlimited saves + iCloud sync
- • Ad-free experience
- • 7-day free trial
Our Philosophy
Music theory should be a tool, not a barrier.
Keys, scales, and chord progressions are concepts that expand what you can do with music. You can write songs without them — but knowing them opens up a whole new world of possibilities. The problem is, learning theory the traditional way is hard.
OtoTheory was created to bridge that gap. You don't need to study theory to use it — just play, experiment, and let the understanding come naturally.
Play along, build along — and the theory follows.
About the Creator
OtoTheory is a music production tool that combines music theory and AI technology, created by TH Quest — a creative studio based in Kamakura, Japan.
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Ready to explore?
Scan to download on iPhone