API reference · Google

google/gemini-3.1-flash-tts

Integrate this model through SandBase's unified API, with production-ready schemas and examples.

AUDIOAsyncOpen model

Production endpoint

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OpenAI-compatible endpoint with unified authentication and usage tracking.

POSThttps://api.sandbase.ai/v1/run

Model IDgoogle/gemini-3.1-flash-tts

Input Schema

7 parameters · 1 required · 6 optional

Parameter	Type	Required	Description
`prompt`	string	Required	The text to convert to speech. Gemini 3.1 Flash TTS supports natural-language prompting for style, pace, accent, and emotional expression — include delivery instructions inline with the text (e.g. 'Say cheerfully: Have a wonderful day!'). Supports expressive audio tags like [sigh], [laughing], [whispering], [short pause] for fine-grained control over delivery. For multi-speaker synthesis, prefix lines with speaker aliases defined in the speakers field (e.g. 'Alice: Hello!\nBob: Hi!'). · Min length: 1 · Max length: 50000
`voice`	string	Optional	Voice preset for single-speaker synthesis. 30 distinct voices are available. Ignored when speakers is set. Popular choices: Kore (strong, firm female), Puck (upbeat, lively male), Charon (calm, professional male), Zephyr (bright, clear female), Aoede (warm, melodic female). · Options: Achernar, Achird, Algenib, Algieba, Alnilam, Aoede, Autonoe, Callirrhoe, Charon, Despina, Enceladus, Erinome, Fenrir, Gacrux, Iapetus, Kore, Laomedeia, Leda, Orus, Pulcherrima, Puck, Rasalgethi, Sadachbia, Sadaltager, Schedar, Sulafat, Umbriel, Vindemiatrix, Zephyr, Zubenelgenubi · Default: "Kore" AchernarAchirdAlgenibAlgiebaAlnilamAoedeAutonoeCallirrhoeCharonDespinaEnceladusErinomeFenrirGacruxIapetusKoreLaomedeiaLedaOrusPulcherrimaPuckRasalgethiSadachbiaSadaltagerSchedarSulafatUmbrielVindemiatrixZephyrZubenelgenubi
`speakers`	object[]	Optional	Multi-speaker voice configuration. When set, enables multi-speaker synthesis where different parts of the text are spoken by different voices. Each speaker needs a voice and a speaker_id (alias) that matches prefixes in the prompt.
`temperature`	number	Optional	Controls the randomness of the speech output. Higher values produce more creative and varied delivery, while lower values make the output more predictable and focused. · Min: 0 · Max: 2 · Default: 1
`language_code`	string	Optional	Language for multilingual synthesis. When set, steers the model to speak in the specified language. If not set, the model auto-detects the language from the text. · Options: Arabic (Egypt), Bangla (Bangladesh), Dutch (Netherlands), English (India), English (US), French (France), German (Germany), Hindi (India), Indonesian (Indonesia), Italian (Italy), Japanese (Japan), Korean (South Korea), Marathi (India), Polish (Poland), Portuguese (Brazil), Romanian (Romania), Russian (Russia), Spanish (Spain), Tamil (India), Telugu (India), Thai (Thailand), Turkish (Turkey), Ukrainian (Ukraine), Vietnamese (Vietnam), Afrikaans (South Africa), Albanian (Albania), Amharic (Ethiopia), Arabic (World), Armenian (Armenia), Azerbaijani (Azerbaijan), Basque (Spain), Belarusian (Belarus), Bulgarian (Bulgaria), Burmese (Myanmar), Catalan (Spain), Cebuano (Philippines), Chinese Mandarin (China), Chinese Mandarin (Taiwan), Croatian (Croatia), Czech (Czech Republic), Danish (Denmark), English (Australia), English (UK), Estonian (Estonia), Filipino (Philippines), Finnish (Finland), French (Canada), Galician (Spain), Georgian (Georgia), Greek (Greece), Gujarati (India), Haitian Creole (Haiti), Hebrew (Israel), Hungarian (Hungary), Icelandic (Iceland), Javanese (Java), Kannada (India), Konkani (India), Lao (Laos), Latin (Vatican City), Latvian (Latvia), Lithuanian (Lithuania), Luxembourgish (Luxembourg), Macedonian (North Macedonia), Maithili (India), Malagasy (Madagascar), Malay (Malaysia), Malayalam (India), Mongolian (Mongolia), Nepali (Nepal), Norwegian Bokmal (Norway), Norwegian Nynorsk (Norway), Odia (India), Pashto (Afghanistan), Persian (Iran), Portuguese (Portugal), Punjabi (India), Serbian (Serbia), Sindhi (India), Sinhala (Sri Lanka), Slovak (Slovakia), Slovenian (Slovenia), Spanish (Latin America), Spanish (Mexico), Swahili (Kenya), Swedish (Sweden), Urdu (Pakistan) Arabic (Egypt)Bangla (Bangladesh)Dutch (Netherlands)English (India)English (US)French (France)German (Germany)Hindi (India)Indonesian (Indonesia)Italian (Italy)Japanese (Japan)Korean (South Korea)Marathi (India)Polish (Poland)Portuguese (Brazil)Romanian (Romania)Russian (Russia)Spanish (Spain)Tamil (India)Telugu (India)Thai (Thailand)Turkish (Turkey)Ukrainian (Ukraine)Vietnamese (Vietnam)Afrikaans (South Africa)Albanian (Albania)Amharic (Ethiopia)Arabic (World)Armenian (Armenia)Azerbaijani (Azerbaijan)Basque (Spain)Belarusian (Belarus)Bulgarian (Bulgaria)Burmese (Myanmar)Catalan (Spain)Cebuano (Philippines)Chinese Mandarin (China)Chinese Mandarin (Taiwan)Croatian (Croatia)Czech (Czech Republic)Danish (Denmark)English (Australia)English (UK)Estonian (Estonia)Filipino (Philippines)Finnish (Finland)French (Canada)Galician (Spain)Georgian (Georgia)Greek (Greece)Gujarati (India)Haitian Creole (Haiti)Hebrew (Israel)Hungarian (Hungary)Icelandic (Iceland)Javanese (Java)Kannada (India)Konkani (India)Lao (Laos)Latin (Vatican City)Latvian (Latvia)Lithuanian (Lithuania)Luxembourgish (Luxembourg)Macedonian (North Macedonia)Maithili (India)Malagasy (Madagascar)Malay (Malaysia)Malayalam (India)Mongolian (Mongolia)Nepali (Nepal)Norwegian Bokmal (Norway)Norwegian Nynorsk (Norway)Odia (India)Pashto (Afghanistan)Persian (Iran)Portuguese (Portugal)Punjabi (India)Serbian (Serbia)Sindhi (India)Sinhala (Sri Lanka)Slovak (Slovakia)Slovenian (Slovenia)Spanish (Latin America)Spanish (Mexico)Swahili (Kenya)Swedish (Sweden)Urdu (Pakistan)
`output_format`	string	Optional	Audio output format. mp3: compressed, small file size (recommended). wav: uncompressed PCM wrapped in WAV (24 kHz, 16-bit mono). ogg_opus: Ogg container with Opus codec, good quality-to-size ratio. · Options: wav, mp3, ogg_opus · Default: "mp3" wavmp3ogg_opus
`style_instructions`	string	Optional	Optional style and delivery instructions prepended to the prompt. Controls expressiveness, accent, pace, tone, and emotional expression using natural language. Use this to separate style control from the text content. Examples: 'Speak warmly and slowly', 'Read this as a dramatic newscast', 'Use a British accent with a cheerful tone', 'Whisper mysteriously'. · Max length: 4000

Output Schema

Field	Type	Description
`id`	string	Unique identifier for the generation task
`status`	string	Task status: pending, running, completed, failed, timeout
`model`	string	Model used for the generation
`outputs`	array	Array of output items
`outputs[].url`	string	URL of the generated artifact
`outputs[].content_type`	string	MIME type (e.g. image/png, video/mp4)
`error`	object \| null	Error details if failed, null on success
`error.type`	string	Machine-readable error type code
`error.message`	string	Human-readable error description

Async Workflow

This model uses asynchronous execution. Submit a request and poll for the result.

Submit — POST to /v1/run, receive an id
Poll — GET /v1/run/{id} until status is completed, failed, or timeout
Retrieve — Read outputs from the completed response

Code Examples

Ready-to-run snippets

# Step 1: Submit
curl -X POST https://api.sandbase.ai/v1/run \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
  "model": "google/gemini-3.1-flash-tts",
  "voice": "Kore",
  "prompt": "I can't believe it worked! [laughing] After all those hours of debugging [sigh] it was just a missing semicolon.",
  "speakers": [
    {
      "voice": "Charon",
      "speaker_id": "Host"
    },
    {
      "voice": "Kore",
      "speaker_id": "DrChen"
    }
  ],
  "temperature": 1,
  "language_code": "English (US)",
  "output_format": "mp3",
  "style_instructions": "Say the following in a warm, conversational tone"
}'

# Step 2: Poll result (replace <id>)
curl https://api.sandbase.ai/v1/run/<id> \
  -H "Authorization: Bearer YOUR_API_KEY"

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