Build Chord Progressions,
Play Along, Learn Along
Import chord progressions of your favorite songs from ChatGPT or Gemini — just copy & paste. Instantly hear them with pro grooves, see Roman numeral analysis, and export as MIDI.
OtoTheory — Use Theory Without Tears
What is OtoTheory?
OtoTheory is a chord progression builder and music theory companion for guitar, bass, keyboard players, and DAW users. Build progressions while listening to backing tracks — swap chords, switch grooves, and hear your ideas come to life in real time. No deep theory knowledge needed.
Import Chord Progressions from AI
Ask ChatGPT or Gemini for any song's chords, then just copy & paste. Instant Roman numeral analysis & backing playback.
DJ-Style Composition
Edit chords while music plays. Never break your creative flow.
15 Groove Patterns
5 categories: Energy, Vibe, Unplugged, Traditional, Synth.
OtoTheory AI
3-layer context analysis suggests chords that fit — sensory, theory, and emotional.
50+ Chord Progression Presets
Axis, Pop Punk, Jazz, Blues, and more. Pick one and start playing.
What You Can Do
Import Chords from AI
Ask ChatGPT or Gemini for any song's chord progression, then just copy & paste into OtoTheory. Instantly see Roman numeral analysis, play with grooves, and export as MIDI. iOS app only.
Play Along, Build Along
Hear your chord progression with full backing tracks — drums, bass, and harmony. Swap chords and switch grooves without stopping playback.
Key & Scale Detection (8 Scales)
Auto-detect key with fit percentage. See diatonic chords and fretboard overlay for guitar, bass, and keyboard.
Split Bar — 2 Chords Per Measure
Place two chords in one bar for more complex progressions like ii-V or the Marusa progression.
Section Management
Organize into Verse, Chorus, Bridge, and more. Customize playback order and export sections as MIDI markers.
MIDI Export — 3 Modes
Export to Logic Pro, Cubase, Ableton, and more. Choose Groove, Groove + Theory, or Chords Only mode.
Free Web Tools
Try OtoTheory in your browser — no download needed.
Chord Progression
Build your song's blueprint with theory-backed insights.
Build progressions with 50+ presets and 19 groove patterns.
Real-time key & scale detection as you compose.
Playful puzzle-like experience keeps your creative flow going.
Find Chords
Visualize the fretboard — connect theory to your instrument.
See scale tones and chord positions on the fretboard in real-time.
Supports guitar, bass, and keyboard views.
Discover new voicings that break out of your usual patterns.
Resources
Quick reference when you need it.
Diatonic, modes, and cadence explained with clear visuals.
A concise guide for quick recall during composition.
Supporting resource for your creative workflow.
My Sketches
Save your sketches — export to DAW when ready.
Save your chord progressions as sketches (Free: 3 local, Pro: unlimited cloud).
Export as Multi-track MIDI to your DAW for final production.
Your creative ideas, always accessible and ready to evolve.
Unlock the Full Experience on iOS
The iOS app takes everything further — real-time backing tracks, AI-powered chord suggestions, and seamless DAW export.
Scan to download on iPhone
Free vs Pro
Start free, upgrade when you're ready.
Free
$0
- ✓ AI chord progression import
- ✓ 50+ chord progression presets
- ✓ 19 groove patterns (4/4 + 6/8 + 12/8 on iOS)
- ✓ All chords (tensions, slash chords)
- ✓ OtoTheory AI (all modes)
- ✓ Section management
- ✓ Key & scale detection
- ✓ Fretboard/keyboard visualization
- ✓ 3 local saves & text export
Pro
7-day free trial · pricing varies by region
- ✓ MIDI/audio export — 3 modes (unlimited)
- ✓ Unlimited saves + iCloud sync
- ✓ Ad-free experience
Frequently Asked Questions
Is OtoTheory free?
Yes. The OtoTheory web tools (chord progression builder, find chords, fretboard visualization, AI chord import) are completely free with no signup required. The iOS app is also free to download with all core features unlocked. Pro is an optional iOS upgrade for MIDI / audio / PDF export and unlimited cloud saves, with a 7-day free trial.
What is the difference between OtoTheory Free and Pro?
Free includes everything you need to compose: AI chord progression import from ChatGPT or Gemini, 50+ presets, 19 groove patterns (4/4 + 6/8 + 12/8 time signatures, iOS), OtoTheory AI suggestions, key and scale detection, fretboard / keyboard visualization, section management, and 3 local saves. Pro (iOS only, 7-day free trial) adds MIDI / audio / PDF export in 3 modes, unlimited saves, iCloud sync, and an ad-free experience.
What can I do on the OtoTheory web tools versus the iOS app?
The web tools cover building chord progressions, finding diatonic chords for any key, visualizing scales on a fretboard, and pasting chord progressions from AI assistants. The iOS app adds offline use, real-time backing playback for full sketching, MIDI / audio / PDF export to your DAW, unlimited cloud-synced sketches, and a Pro tier with a 7-day free trial.
Does OtoTheory work for guitar, bass, and keyboard?
Yes. The fretboard visualization supports guitar, bass, and keyboard. You can switch instrument view at any time. Chord shapes, scale tones, and diatonic chords are displayed in positions appropriate for each instrument.
Can I import chord progressions from ChatGPT or other AI tools?
Yes. OtoTheory has a Paste Chords feature: ask ChatGPT, Claude, or Gemini for any song's chord progression, then copy and paste the response into OtoTheory. The parser recognizes chord names, section labels like [Verse] and [Chorus], pipe-separated bars, and various notation formats. You then get instant Roman numeral analysis and can play it with grooves.
Do I need to sign up to use OtoTheory?
No. The web tools work without any signup or account. The iOS app also requires no signup; a Sign in with Apple option is provided only for optional iCloud sync of saved sketches on Pro.
Is there a free trial of OtoTheory Pro?
Yes. OtoTheory Pro on iOS includes a 7-day free trial. You can cancel anytime in your Apple ID subscription settings before the trial ends and you will not be charged.
More questions? See the full FAQ.
Explore More
Start Building Your Chord Progression
Try the free web tools or download the iOS app for the full experience.