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Music Theory Roman Numeral Analysis
x402
Music Theory Roman Numeral Analysis is a paid API for AI agents from music-theory.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Analyzes a chord progression in a given key and returns Roman numeral notation including inversions, borrowed chords, and secondary dominants.
Price / call$0.02
Success—
StatusUnknown
How this service works
Roman numeral analysis of a chord progression in a key: numerals, inversions, borrowed chords, secondary dominants.
Output
Returns a list of Roman numeral labels for each chord in the progression, including inversion notation, diatonic status, degree from tonic, borrowed chord flags, and secondary dominant roles, plus a summary and any unrecognized chords.
Example use cases
Songwriting harmonic analysis
“I wrote a progression in G major: G Em C D7 Am D7 G — can you label each chord with Roman numerals and tell me which ones are diatonic, borrowed, or secondary dominants?”
Music theory homework check
“My homework asks me to analyze the progression Dm G7 C Fmaj7 Am7 E7 in C major using Roman numerals with inversions — can you work that out for me?”
Identifying borrowed chords in a song
“The song I'm transcribing is in A minor and uses Am F C G E7 — can you give me the Roman numeral analysis and flag any borrowed or non-diatonic chords?”
Technical details
Endpoint
GEThttps://music-theory.x402tookit.com/roman-numerals?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need structured Roman numeral harmonic analysis of a chord progression in a specific key, including identification of inversions, borrowed chords, and secondary dominants. Prefer this over manual analysis or general music info APIs when you need machine-readable harmonic function labels for each chord.
Side effects
- Unrecognized chord symbol returns it in 'notChecked' array with partial results
- Invalid or ambiguous key string may return null key or degraded analysis
- Chords with complex extensions may not be fully analyzed
- Missing required 'key' or 'progression' query parameter returns an error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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