Cartesia Voice Cloning API + MCP vs Fish Audio Voice Cloning API

Cartesia Voice Cloning API + MCP

Instant clones from 10 seconds of audio, up to 60 seconds used on Sonic 3.6. No consent or speaker verification in the clone API.

Fish Audio Voice Cloning API

Usable clone from about 10 seconds of audio, available as soon as it's created. No consent or speaker verification in the API.

Cartesia Voice Cloning API + MCP

1. Send Cartesia-Version on every call. The clone endpoint lists it as a required header
2. Pass the speaker's recorded language. A clone is built from one language, add others with the accents API
3. Keep IVC uploads under 16 MB
4. Don't blind-retry POST /voices/clone. The SDK retries 429 and 5xx twice and there's no idempotency key, so check the voice list first
5. Poll a Pro clone fine-tune until it finishes before using the voice ID

Fish Audio Voice Cloning API

1. Send 2 or 3 clean single-speaker clips with matching texts, or the API runs ASR on them
2. Pass the model _id as reference_id in TTS. Check state before relying on it
3. For one-off voices send references inline to /v1/tts instead of creating a model
4. Send the model: voice-design-1 header on voice design calls
5. Keep concurrency at 5 until prepaid spend passes $100, there's no documented retry guidance