MusicGPT API vs Stable Audio API

MusicGPT API

A public OpenAPI 3.1 file with 27 operations, llms.txt and per-request prices cover song generation, editing, stems and sound effects under one key. No status page, SLA, security.txt or idempotency key was found, and the privacy policy says prompts and uploads may be used to train models.

Stable Audio API

Pay-as-you-go credits, $0.26 a 3.0 generation and $0.20 on 2.5, failures free. Stable Audio 3.0 is async only, with polling and no webhook, and inpaint stays on 2 and 2.5.

MusicGPT API

1. Send the key as the raw Authorization header value. The docs show no Bearer prefix
2. Budget two songs for each music request. POST /v2/MusicAI returns two versions and the price is per song
3. Save task_id and poll GET /v1/byId with conversionType, or set webhook_url. Music AI V2 sends up to seven webhooks a request
4. Pass model explicitly. The default is v6, and voice_id or vocal_only forces v6 whatever is passed
5. Do not retry a create blindly after a timeout. No idempotency key is documented, so a retry may bill again

Stable Audio API

1. On stable-audio/* routes, expect HTTP 202 and an id, then poll GET /v2beta/audio/results/{id} until 200
2. Send accept: audio/* for raw bytes, not base64 JSON
3. Set duration. It defaults to 190 seconds on 3.0
4. Wait 60 seconds after a 429 before the next call
5. Use the stable-audio-2 routes for inpainting. 3.0 has no inpaint route