Gemini TTS

POST/v1/run

Gemini TTS by Google - convert text to natural-sounding speech with AI. Supports multiple voices, languages, emotions, and speaking styles for content creation and accessibility.

Request body

Submit an async generation request. The model field selects the model; other fields are model-specific input parameters.

stringmodelrequired

Model identifier. Set to google/gemini-tts.

Default: google/gemini-tts

stringpromptrequired

The text to convert to speech. Gemini 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!'). For multi-speaker synthesis, prefix lines with speaker aliases defined in the speakers field (e.g. 'Alice: Hello!\nBob: Hi!'). Supports inline pace/style markers like [slowly], [whispering], [excited], [extremely fast].

Optional<string>output_format

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.

Allowed values: wav, mp3, ogg_opus

Default: mp3

Optional<string>style_instructions

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'.

Optional<string>language_code

Language for multilingual synthesis. When set, steers the model to speak in the specified language. Supports 24 GA languages and 60+ Preview languages. If not set, the model auto-detects the language from the text.

Allowed values: 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)

Optional<array<object>>speakers

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. Requires gemini-2.5-pro-tts or gemini-2.5-flash-tts model. Not supported with gemini-2.5-flash-lite-preview-tts.

Optional<string>voice

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).

Allowed values: 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

Optional<number>temperature

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.

Range: 0 to 2

Default: 1

Response Schema

The submit endpoint returns a run response. If its status is pending or running, poll GET /v1/run/{id} with the returned opaque ID until it reaches a terminal state.

stringidrequired

Opaque SandBase run identifier. Use it exactly as returned; no prefix is guaranteed.

stringstatusrequired

Current public run status.

Allowed values: pending, running, completed, failed, timeout

Optional<string>model

Public SandBase model name used for this run.

Optional<array<object>>outputs

Present only for completed runs. Each object is capability-specific; inspect the selected model schema for its fields.

Optional<object>error

Present only for failed or timeout runs. Contains a public error type and sanitized message.

Optional<string>error.type

Stable public error category.

Optional<string>error.message

Sanitized error message safe to show to clients.

Optional<object>usage

Usage details when available.

Model capabilities

array<string>capability_tagsrequired

Capabilities declared by the model registry.

Default: text-to-speech

stringexecution_moderequired

Execution mode declared by the model registry.

Default: async

# 1. Submit a generation request
curl -X POST https://api.sandbase.ai/v1/run \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "google/gemini-tts",
  "prompt": "Host: Welcome back to AI Frontiers, the podcast where we explore the latest breakthroughs in artificial intelligence. Today we have a very special guest. Doctor Chen, thank you for joining us!\nDrChen: Thanks for having me! I'm excited to be here.\nHost: So, let's dive right in. Your recent paper on neural architecture search has been making waves. Can you tell our listeners what inspired this research?\nDrChen: Absolutely. It all started when we noticed that most existing approaches were optimizing for the wrong metrics. We asked ourselves, what if we could let the model design itself?",
  "output_format": "mp3",
  "voice": "Kore"
}'

# 2. If the response is still running, poll the returned id
curl https://api.sandbase.ai/v1/run/f3d2e8a1-7c4b-4a12-9d2e-123456789abc \
  -H "Authorization: Bearer $SANDBASE_API_KEY"

Response202 Accepted

{
  "id": "f3d2e8a1-7c4b-4a12-9d2e-123456789abc",
  "model": "google/gemini-tts",
  "status": "running"
}