# POST /v1/music/plan (ElevenLabs API)
Base URL: https://api.elevenlabs.io
Auth: xi-api-key: <ELEVENLABS_API_KEY>
Last verified: 2026-09-03

> Generate Composition Plan

## Critical Gotchas
* Authentication uses the non-standard `xi-api-key` header, not `Authorization: Bearer`. Sending a Bearer token returns HTTP 401.
* Text-to-speech responses are raw binary audio, not JSON. Write the body to a file (`--output speech.mp3`) rather than parsing it.

## cURL
curl -X POST 'https://api.elevenlabs.io/v1/music/plan' \
  -H "xi-api-key: $ELEVENLABS_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"prompt":"string","music_length_ms":0}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| prompt | body | string | Yes | A simple text prompt to compose a pla... |
| music_length_ms | body | integer | No | The length of the composition plan to... |
| source_composition_plan | body | object | No | An optional composition plan to use a... |

## Response (200 OK)
{"negative_global_styles":["metal"],"positive_global_styles":["pop"]}

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