Chord notes from root API

Builds the notes of a chord from a root and quality (maj, min, 7, dim, aug, sus2/4, m7b5, 9, add9 and more) and returns note names, MIDI numbers and frequencies. Answers 'What notes are in Cmaj?', 'Spell a G dominant 7 chord.'.

Price$0.04per request

MethodPOST

Route/v1/music/chord-notes

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

musicchordharmonytriadseventhvoicingtheorynotesaudio

API URLhttps://x402.hexl.dev/v1/music/chord-notes

Integration docs

Example request

{
  "root": "C",
  "quality": "maj"
}

Example response

{
  "root": "C4",
  "quality": "maj",
  "chordName": "C",
  "fullName": "C major triad",
  "intervals": [
    0,
    4,
    7
  ],
  "notes": [
    "C4",
    "E4",
    "G4"
  ],
  "pitchClasses": [
    0,
    4,
    7
  ],
  "midi": [
    60,
    64,
    67
  ],
  "frequencies": [
    261.6256,
    329.6276,
    391.9954
  ]
}

Input schema

{
  "type": "object",
  "required": [
    "root"
  ],
  "properties": {
    "root": {
      "type": "string",
      "examples": [
        "C",
        "G",
        "Bb"
      ]
    },
    "quality": {
      "type": "string",
      "examples": [
        "maj",
        "min",
        "7",
        "maj7",
        "dim",
        "sus4"
      ]
    },
    "octave": {
      "type": "number",
      "examples": [
        4
      ]
    },
    "a4": {
      "type": "number"
    },
    "preferFlats": {
      "type": "boolean"
    }
  }
}

Output schema

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