# Music Note Parser (Scientific Pitch Notation)

> Music Note Parser (Scientific Pitch Notation) is a paid API for AI agents from music.openverbs.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Parses a note in scientific pitch notation (e.g. 'A4', 'C#5', 'Bb3') into its letter, accidental, pitch class (0–11), octave, MIDI number, and frequency in Hz.

## Facts

- Endpoint: POST https://music.openverbs.com/v1/note
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/music-note-parser-scientific-pitch-notation-b0739f1c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SKAn3kdEDdCsmNFIcq2KQ

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-note-parser-scientific-pitch-notation-b0739f1c -d '<json body>'
```

Example prompt: Parse the note 'C#5' for me — I need its pitch class, MIDI number, and frequency in Hz.

## When to prefer this

Use this endpoint when you need to programmatically decompose a note written in scientific pitch notation into its acoustic and MIDI properties. Ideal for music theory tools, synthesizer apps, tuners, or any workflow that needs frequency, pitch class, or MIDI number from a human-readable note name. Prefer this over manual lookup tables or formula-based computation when you want a validated, authoritative parse.

## Known failure modes

- Invalid or malformed note string (e.g. 'Z4', 'C##5') returns an error
- Note out of MIDI range may return an error or null MIDI number
- Empty or missing 'note' field returns a validation error
- Ambiguous enharmonic spellings may be normalized or rejected

## How this service works

Parse a note in scientific pitch notation (e.g. "A4", "C#5", "Bb3") into its letter, accidental, pitch class (0..11), octave, MIDI number and frequency in Hz (A4 = 440 Hz).

## Output

Returns the note's letter (e.g. 'C'), accidental (e.g. '#', 'b', or none), pitch class (integer 0–11), octave number, MIDI note number (0–127), and frequency in Hz (A4 = 440 Hz).

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "note"
     ],
     "properties": {
      "note": {
       "type": "string",
       "maxLength": 8,
       "minLength": 1,
       "description": "e.g. \"A4\", \"C#5\", \"Bb3\"."
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/music-note-parser-scientific-pitch-notation-b0739f1c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from music.openverbs.com](https://www.zero.xyz/host/music.openverbs.com/llms.txt)