models/Google/Gemini 3.1 Flash TTS
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Gemini 3.1 Flash TTS

audio-tts
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Newest audio model from Google introduces granular audio tags that give you precise control to direct AI speech for expressive audio generation.

MODALITIES
audio
USAGE
161.8M
0% market share
RELEASED
2026-05-22

Gemini 3.1 Flash TTS (google/gemini-3.1-flash-tts) is a audio-tts model from Google, released 2026-05-22. Pricing via AIgateway: $0.0000 per 1K chars. Capabilities: tools, vision, json. Call it via https://api.aigateway.sh/v1/audio/speech — set model="google/gemini-3.1-flash-tts". Best for: Voiceovers, IVR, Audiobooks.

model · google/gemini-3.1-flash-ttsfamily · Gemini 3

Use this model

model: google/gemini-3.1-flash-tts
curl https://api.aigateway.sh/v1/audio/speech \
  -H "Authorization: Bearer $AIGATEWAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"google/gemini-3.1-flash-tts","voice":"alloy","input":"Hello, world."}'

Capabilities

Tool callingVisionJSON mode

Strengths

  • Natural speech synthesis

Use cases

VoiceoversIVRAudiobooks

Adoption

161.8M tokens
428.2K requests · 0% of tracked market volume
See the full leaderboard →
Aggregate usage across the open model ecosystem (as of 2026-05-22).

Pricing

Per 1K chars$0.0000
You pay pass-through · 5% applied at credit top-up, not per-call.
See API example →CompareAPI referenceSee usage ranking →

Collections

More audio models →More from Google →Frontier models →Free-tier models →
API schema

Call Gemini 3.1 Flash TTS from any OpenAI SDK

POST https://api.aigateway.sh/v1/audio/speech·Content-Type: application/json·Auth: Bearer sk-aig-...

Request body

json
{
  "model": "google/gemini-3.1-flash-tts",
  "input": "Hello from AIgateway.",
  "voice": "alloy",
  "format": "mp3",        // mp3 | wav | flac | opus
  "speed": 1.0
}

Response

json
// Binary audio stream in the requested format (mp3 by default).
// Content-Type: audio/mpeg  (or audio/wav, audio/flac, audio/opus)
// Read the response body directly to a file.

Quickstart

from openai import OpenAI
client = OpenAI(base_url="https://api.aigateway.sh/v1", api_key="sk-aig-...")

r = client.audio.speech.create(model="google/gemini-3.1-flash-tts", voice="alloy", input="Hello world.")
r.stream_to_file("out.mp3")

Errors

401authentication_errorInvalid or missing API key
402insufficient_creditsWallet empty (PAYG only)
404not_foundUnknown model or endpoint
429rate_limit_errorOver per-minute limit — see Retry-After header
500server_errorUpstream provider failed (retryable)
503service_unavailableUpstream saturated (retryable)
Full docs →API reference →OpenAPI spec →llms.txt →

Frequently asked questions

What is Gemini 3.1 Flash TTS?
Newest audio model from Google introduces granular audio tags that give you precise control to direct AI speech for expressive audio generation. It is a audio-tts model from Google, accessible via AIgateway's OpenAI-compatible API at slug google/gemini-3.1-flash-tts.
How much does Gemini 3.1 Flash TTS cost via AIgateway?
Pass-through pricing plus a 5% platform fee applied at top-up. See the pricing panel on this page for exact rates.
How do I call Gemini 3.1 Flash TTS from my code?
Point the OpenAI SDK at https://api.aigateway.sh/v1 with your AIgateway key and set model to "google/gemini-3.1-flash-tts". The request and response shapes match OpenAI exactly.
Does Gemini 3.1 Flash TTS support streaming, tool calling, vision, and JSON mode?
Streaming — no. Tool calling — yes. Vision — yes. JSON mode — yes. Prompt caching — no.
What are the best use cases for Gemini 3.1 Flash TTS?
Voiceovers, IVR, Audiobooks. Key strengths: Natural speech synthesis.
Can I bring my own Google API key (BYOK)?
Yes. Attach a Google key in your AIgateway dashboard and this model flips to pass-through — you pay Google directly and AIgateway waives the 5% platform fee on those calls.