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Google Gemini 3.1 Flash TTS – Text-to-Speech
Google Gemini 3.1 Flash TTS – Text-to-Speech is a paid API for AI agents from audio.withzero.xyz, paid per call via MPP, $0–$0.01/call (observed), status healthy (last checked 2026-09-15, last successful call 2026-09-06).
Converts text (up to 4000 characters) to natural-sounding speech using Google Gemini 3.1 Flash TTS and returns a hosted WAV audio URL.
Price / call$0–$0.01observed
Success75%
StatusHealthy
How this service works
Convert text to natural-sounding speech with Google Gemini 3.1 Flash TTS and return a hosted audio URL.
Output
Returns a JSON object containing a hosted WAV audio URL (24kHz mono), the MIME type, file size in bytes, approximate audio duration in seconds, the model name used, and the USDC price charged for the request.
Example use cases
Example prompt
“Can you read this aloud using Google Gemini 3.1 Flash TTS with the Kore voice: 'Welcome to our platform. We're excited to have you here and look forward to helping you get started today.'”
Technical details
Endpoint
POSThttps://audio.withzero.xyz/api/v1/speech/gemini-3.1-flash-ttsWhen to prefer
Choose this endpoint when you specifically want Google Gemini 3.1 Flash TTS quality audio synthesis with a hosted URL returned immediately. Prefer this over alternatives when you need Gemini's specific voice characteristics, require a WAV format output at 24kHz mono, or want a zero-cost per-call TTS option backed by Gemini's model.
Side effects
- Input text empty or missing — 400 validation error
- Text exceeds 4000 character limit — 400 validation error
- Invalid or unrecognized voice name — may fall back to default or return error
- Upstream Gemini TTS API unavailable — 502/503 error
- Audio hosting failure — URL may not be accessible
- Rate limiting from upstream provider — 429 error
Input
{
"input": "Welcome to our platform. We're excited to have you here and look forward to helping you get started today.",
"voice": "Kore"
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | string | The text to convert to speech (1–4000 characters). |
| voicerequired | string | Voice to speak with. Defaults to "Kore". |
Output
{
"url": "https://storage.googleapis.com/withzero/audio/d707e4da-99ef-4c5a-8de6-d80cbcbd566a.wav",
"model": "google/gemini-3.1-flash-tts-preview",
"seconds": 6.1,
"mimeType": "audio/wav",
"sizeBytes": 293804,
"price_usdc": "0.00424"
}Schema · Response
| Field | Type | Description |
|---|---|---|
| urlrequired | string | Hosted URL of the generated audio (WAV, 24kHz mono). |
| modelrequired | string | The model that produced the audio. |
| secondsrequired | number | Approximate duration of the generated audio in seconds. |
| mimeTyperequired | string | Content type of the generated audio. |
| sizeBytesrequired | number | Size of the generated audio in bytes. |
| price_usdcrequired | string | The amount charged for this request, in USDC. |
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