# Music Production Calc: Fret Note Lookup

> Music Production Calc: Fret Note Lookup is a paid API for AI agents from music-production-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Returns the note name, MIDI number, and frequency in Hz for any fret position on guitar, bass, ukulele, or violin strings, with support for alternate tunings.

## Facts

- Endpoint: GET https://music-production-calc.x402tookit.com/fret-note?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/music-production-calc-fret-note-lookup-c652f4c8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QYli3DENiN1wZEwGH0T5q

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability music-production-calc-fret-note-lookup-c652f4c8
```

Example prompt: What note, MIDI number, and frequency do I get on fret 7 of string 3 on a guitar tuned down 2 semitones, using standard A4 at 440 Hz?

## When to prefer this

Use this endpoint when you need precise note name, MIDI number, or frequency data for a specific fret and string position on a guitar, bass, ukulele, or violin — especially when alternate tunings or non-standard A4 reference pitches are involved. It is ideal for music production tools, fretboard educators, MIDI mapping assistants, and tuning analysis workflows where instrument-specific string/fret lookup is required rather than general music theory computation.

## Known failure modes

- Missing required parameters (instrument, string, fret) returns a validation error
- Fret number out of range 0–24 or string number out of valid range for the instrument returns an error
- Invalid instrument name (not guitar, bass, ukulele, or violin) returns an error
- A4 reference pitch outside 400–480 Hz range returns an error
- Tuning offset outside -12 to 12 semitones returns an error

## How this service works

Note name, MIDI number and Hz at a fret on guitar, bass, ukulele or violin strings, with alternate tunings.

## Output

Returns the sharp and flat note name, MIDI number, frequency in Hz, open string note and MIDI number, 12th fret octave note, the A4 reference pitch used, fret number, string number, instrument, and tuning offset in semitones.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "instrument",
      "string",
      "fret"
     ],
     "properties": {
      "a4": {
       "type": "number",
       "description": "Reference pitch for A4 in Hz, 400 to 480 (default 440)"
      },
      "fret": {
       "type": "integer",
       "description": "Fret 0 (open) to 24"
      },
      "string": {
       "type": "integer",
       "description": "String number, 1 = highest-pitched in normal numbering (guitar 6 = low E)"
      },
      "instrument": {
       "type": "string",
       "description": "guitar, bass, ukulele or violin"
      },
      "tuningOffset": {
       "type": "integer",
       "description": "Tune the whole instrument by semitones, -12 to 12 (-2 = whole step down); default 0"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "a4Used": {
       "type": [
        "null",
        "number"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "noteFlat": {
       "type": [
        "null",
        "string"
       ]
      },
      "noteSharp": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "fretNumber": {
       "type": [
        "null",
        "number"
       ]
      },
      "instrument": {
       "type": [
        "null",
        "string"
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/music-production-calc-fret-note-lookup-c652f4c8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from music-production-calc.x402tookit.com](https://www.zero.xyz/host/music-production-calc.x402tookit.com/llms.txt)