# OpenRouter APIs — Fish Audio: S1 (fish-audio/s1)

Guide for calling every confirmed OpenRouter API that serves `fish-audio/s1`.

Model page: https://openrouter.ai/fish-audio/s1
Create an API key: https://openrouter.ai/settings/keys

## Authentication

Send this header with every request:

- Authorization: Bearer $OPENROUTER_API_KEY

## Text-to-Speech API

Synthesize audio with `fish-audio/s1` through OpenRouter's Text-to-Speech API.

Docs: https://openrouter.ai/docs/api/api-reference/tts/create-speech

### Endpoint

POST https://openrouter.ai/api/v1/audio/speech

Headers:
- Content-Type: application/json

### Request fields (fish-audio/s1)

- model: string (required) — `"fish-audio/s1"`
- input: string (required) — text to synthesize
- voice: string (optional) — provider-specific voice identifier
- response_format: "mp3" | "pcm" (optional) — output audio encoding; defaults to pcm

### Response

Success returns raw audio bytes, not JSON.

- `Content-Type` identifies the audio encoding, such as `audio/mpeg` or `audio/pcm`.
- `X-Generation-Id` identifies the billed generation.
- Write the response body directly to an audio file; do not call `response.json()`.

### Examples

#### Text to Speech

```bash
curl https://openrouter.ai/api/v1/audio/speech \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  --output output.mp3 \
  -d '{
  "model": "fish-audio/s1",
  "input": "The warm light flows across the OpenRouter office as the evening settles in and the routing never stops. One interface, hundreds of models. Ready when you are.",
  "voice": "b347db033a6549378b48d00acb0d06cd",
  "response_format": "mp3"
}'
```

### Error differences

- 400 — malformed audio input or an audio option the routed provider does not support
- 502 — the upstream audio operation failed

## Errors

Failures return `{"error": {"code": <number>, "message": <string>}}` with the HTTP status:

- 400 — malformed request or an unsupported parameter
- 401 — missing or invalid API key
- 402 — insufficient credits
- 403 — spend limit reached, key disabled, or access blocked
- 404 — unknown model or no provider can serve the request
- 429 — rate limited; retry with backoff
- 502 — the operation failed upstream; failed generations are not billed

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Canonical version of this document: https://openrouter.ai/fish-audio/s1/llms.txt