curl --request POST \
  --url https://api.iotools.cloud/v1/tool/musical-note-frequency-generator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "mode": "note",
  "refHz": "440",
  "noteName": "A4",
  "inputFreq": "440"
}
'

{
  "tool": "musical-note-frequency-generator",
  "tool_version": "1.0.1",
  "outputs": {
    "resultNoteName": "A4",
    "resultFrequency": "440.00 Hz",
    "midiNote": "69",
    "wavelength": "77.955 cm",
    "centsOffset": "+0.00 ¢ from A4",
    "octaveTable": [
      {
        "note": "C4",
        "frequency": "261.63 Hz",
        "midi": "60",
        "wavelength": "1.3110 m"
      },
      {
        "note": "C#4",
        "frequency": "277.18 Hz",
        "midi": "61",
        "wavelength": "1.2375 m"
      },
      {
        "note": "D4",
        "frequency": "293.66 Hz",
        "midi": "62",
        "wavelength": "1.1680 m"
      },
      {
        "note": "D#4",
        "frequency": "311.13 Hz",
        "midi": "63",
        "wavelength": "1.1024 m"
      },
      {
        "note": "E4",
        "frequency": "329.63 Hz",
        "midi": "64",
        "wavelength": "1.0406 m"
      },
      {
        "note": "F4",
        "frequency": "349.23 Hz",
        "midi": "65",
        "wavelength": "98.217 cm"
      },
      {
        "note": "F#4",
        "frequency": "369.99 Hz",
        "midi": "66",
        "wavelength": "92.704 cm"
      },
      {
        "note": "G4",
        "frequency": "392.00 Hz",
        "midi": "67",
        "wavelength": "87.501 cm"
      },
      {
        "note": "G#4",
        "frequency": "415.30 Hz",
        "midi": "68",
        "wavelength": "82.590 cm"
      },
      {
        "note": "A4",
        "frequency": "440.00 Hz",
        "midi": "69",
        "wavelength": "77.955 cm"
      },
      {
        "note": "A#4",
        "frequency": "466.16 Hz",
        "midi": "70",
        "wavelength": "73.579 cm"
      },
      {
        "note": "B4",
        "frequency": "493.88 Hz",
        "midi": "71",
        "wavelength": "69.450 cm"
      }
    ]
  },
  "credits_used": 3,
  "credits_remaining": null
}