Reference

Music chord analyzer API

Spell a chord name (e.g. Cmaj7, Am, G7) into its constituent notes and interval formula, or name a chord from a set of notes — the value-add being the bidirectional music-theory interval computation over the 12-tone scale. Answers 'what notes are in Cmaj7', 'name the chord C E G', 'intervals of a minor triad', 'spell a Dsus4 chord'.

Price$0.01per request

MethodPOST

Route/v1/ref/chord

StatusLive

MIME typeapplication/json

Rate limit60/minute

CacheNo cache

refmusicchordnotestheoryintervalsharmonyscale

API URLhttps://x402.hexl.dev/v1/ref/chord

Integration docs

Example request

{
  "chord": "Cmaj7"
}

Example response

{
  "mode": "spell",
  "chord": "Cmaj7",
  "root": "C",
  "quality": "maj7",
  "notes": [
    "C",
    "E",
    "G",
    "B"
  ],
  "intervals": [
    "P1",
    "M3",
    "P5",
    "M7"
  ],
  "semitones": [
    0,
    4,
    7,
    11
  ]
}

Input schema

{
  "type": "object",
  "properties": {
    "chord": {
      "type": "string",
      "examples": [
        "Cmaj7"
      ]
    },
    "notes": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "examples": [
        [
          "C",
          "E",
          "G"
        ]
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}