Fish Audio S2.1 Pro

Production multilingual speech with stateless voice cloning — send a sample, get that voice back.

POST/v1/media/queue

$0.0317/1K chars

Overview

S2.1 Pro is Fish Audio's production text-to-speech model, built for multilingual voice applications, expressive narration, and dialogue synthesis. It is the only speech model on YepAPI that supports stateless voice cloning: attach a short reference sample to the request and the generated speech mimics that voice. There is no voice to create, upload, or manage beforehand.

Property	Value
Model ID	`fish-audio/s2.1-pro`
Alias	`fish`
Upstream Model	`fish-audio/s2.1-pro`
Category	Text to Speech
Languages	multilingual
Output	`mp3` (default) or `pcm`
Pricing	$0.0317 per 1,000 characters

Usage

All media models use the async job queue. Submit a job, then poll for the result.

Step 1: Submit Job

const res = await fetch('https://api.yepapi.com/v1/media/queue', {
  method: 'POST',
  headers: {
    'x-api-key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'fish-audio/s2.1-pro',
    prompt: 'Your text to speak goes here.',
  }),
});
const { data } = await res.json();
// data.jobId — use this to poll for results

curl -X POST https://api.yepapi.com/v1/media/queue \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "fish-audio/s2.1-pro", "prompt": "Your text to speak goes here."}'

Step 2: Poll for Result

const status = await fetch(`https://api.yepapi.com/v1/media/status/${data.jobId}`, {
  headers: { 'x-api-key': 'YOUR_API_KEY' },
});
const { data: job } = await status.json();
// job.status — "pending" | "processing" | "completed" | "failed"
// job.result.audio — { mimeType, base64 } when completed

curl https://api.yepapi.com/v1/media/status/JOB_ID \
  -H "x-api-key: YOUR_API_KEY"

Write the audio to a file:

import { writeFileSync } from 'node:fs';

writeFileSync('speech.mp3', Buffer.from(job.result.audio.base64, 'base64'));

Request Body

Parameter	Type	Required	Description	Default
`model`	`string`	Yes	`fish-audio/s2.1-pro`	—
`prompt`	`string`	Yes	The text to speak (max 50,000 bytes)	—
`options.voice`	`string`	No	Voice identifier	provider default
`options.outputFormat`	`string`	No	`mp3` (default) or `pcm`	`mp3`
`options.speed`	`number`	No	Playback speed multiplier. Honoured only by models that support it	`1.0`

Voices

Fish Audio ships no fixed voice catalogue — omit options.voice and the provider selects its default, or steer the delivery through the input text itself.

Features

Stateless voice cloning from a single reference sample
No voice enrolment step — the sample travels with the request
Open-ended natural-language control of speaking style
Multilingual narration and dialogue synthesis

Voice cloning

Attach a reference sample and the generated speech mimics that voice. Nothing is stored — the sample travels with the request, so there is no voice to create or manage beforehand.

const res = await fetch('https://api.yepapi.com/v1/media/queue', {
  method: 'POST',
  headers: {
    'x-api-key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'fish-audio/s2.1-pro',
    prompt: 'This sentence is spoken in the cloned voice.',
    audioData: {
      mimeType: 'audio/mpeg',
      base64: '<base64-encoded voice sample>',
    },
    options: {
      // Optional transcript of the sample — improves fidelity.
      referenceText: 'I used to rule the world.',
    },
  }),
});

Parameter	Type	Required	Description
`audioData.mimeType`	`string`	Yes	MIME type of the reference sample, e.g. `audio/mpeg` or `audio/wav`
`audioData.base64`	`string`	Yes	Base64-encoded reference audio (max 15 MB decoded)
`options.referenceText`	`string`	No	Transcript of the sample — improves cloning fidelity

Warning

audioData is rejected on every other speech model. Use fish-audio/s2.1-pro for cloning.

Billing

Speech is billed on the length of the input text, in UTF-8 bytes — for English text one byte is one character. The cost is known before synthesis starts, so the balance check at submit time quotes the exact final charge. Jobs have a $0.01 minimum.

Under the Hood

Fish Audio S2.1 Pro

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