Chord Progression Builder for Songwriters
Pick a key. Place a chord. Song Cage shows you what fits next — based on the chords around it, the melody above it, and the theory behind it. A chord progression generator powered by music theory, not AI.
Chord Suggestions That Know Where You've Been
Most chord apps give you a static list of chords in a key. Song Cage reads your entire progression — the chord before, the chord after, and the melody notes at that beat — and ranks every option by how well it fits the context you've already built.
- Suggestions scored by harmonic context, not random order
- Detects multi-chord patterns across section boundaries
- Melody-aware — chords rank higher when they match your notes
- Extensions suggested only when they improve voice leading
Diatonic, Borrowed, and Secondary Dominants
Song Cage doesn't limit you to the 7 chords in your key. See borrowed chords from parallel modes — the bVII, the iv, the bIII — and secondary dominants with resolution arrows showing where they want to go. Every chord is labeled by function so you learn the theory while you write.
- 7 diatonic chords — the foundation of your key
- Borrowed chords from parallel minor/major and other modes
- Secondary dominants with V→I resolution arrows
- Extensions: maj7, sus2, sus4, add9, 7, and more
- Roman numeral labels — understand every chord's function
Change Keys Without Getting Lost
The modulation panel maps pivot chord routes between any two keys. Select a target key and see every chord shared between your current key and the destination — ranked by harmonic strength, with full routes showing how to get there and back.
- Pivot chords between any two keys, ranked by strength
- Full modulation routes — current → pivot → dominant → new tonic
- Return routes to get back to your original key
- Chord Exits — see every key where any chord is diatonic
Common Questions
How does Song Cage suggest chord progressions without AI?
Song Cage uses music theory — not a machine learning model — to generate chord suggestions. When you select a position on the timeline, the app reads the chord before it, the chord after it, and the melody notes at that beat, then scores every available chord based on harmonic context, voice leading smoothness, and common cadence patterns. The result is a chord progression generator powered by the same theory a trained musician would use.
What types of chords does Song Cage include?
Song Cage includes 37 chords per key across three categories: diatonic chords (the 7 chords naturally in your key), borrowed chords from parallel modes (modal interchange), and secondary dominants with resolution arrows. Each chord also has extensions like maj7, sus2, sus4, add9, and more — suggested only when they improve the voice leading from the previous chord.
Can I use Song Cage as a chord progression generator?
Yes. Song Cage works as a chord progression generator that suggests chords based on your musical context rather than generating random sequences. Pick a key, place your first chord, and the palette immediately ranks what should come next — factoring in the chords around it and any melody notes you've written. You stay in control of every choice while the app handles the theory.
Everything Works Together
Lyric Writing
Rhymes, slant rhymes, and synonyms — click any word and the tools appear instantly.
Guitar Songwriting
Fretboard diagrams, multiple voicings, and capo transposition for every chord.
Music Theory
Learn borrowed chords, modulation, and voice leading naturally as you write songs.
Start Building Chord Progressions Today
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