GoogleFastHigh

Gemini 3.1 Flash TTS

Google Gemini 3.1 Flash native-audio TTS via Replicate. Style instructions (separate from the spoken text) plus 30 preset voices and 40+ language/locale codes, with inline markup tags for expressive delivery ([sigh], [whispering], [shouting], etc.).

299 credits

per 1000 characters (input text + generated speech)

Native-audio TTS powered by Gemini 3.1 Flash

Separate style-instruction field (prompt) independent from the spoken text

30 preset voices

40+ language/locale codes (BCP-47), including Korean, Japanese, Spanish, French, German, and more

Inline markup tags ([sigh], [laughing], [whispering], [shouting], [extremely fast]) for expressive delivery

Run it right now

Test this model instantly in the Console Playground — no code required

Use with AI Assistant

Copy usage instructions for Claude, ChatGPT, or other AI

llms.txtllms.txt ↗

Quick Start

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "google/gemini-3.1-flash-tts",
  "input": {
    "prompt": "Say this in a calm, professional tone, like a documentary narrator.",
    "text": "오늘 소개할 제품은 최신 무선 이어폰입니다. 뛰어난 음질과 편안한 착용감을 동시에 제공합니다.",
    "voice": "Kore",
    "language_code": "ko-KR"
  }
}'

Parameters

Parameter	Type	Required	Default	Description
`prompt`	string	No	Say the following.	Style instructions to control how the text is spoken. Use natural language to describe the desired tone, pace, accent, and emotion. For example: 'Say this in a calm, professional tone' or 'Speak with excitement and energy'. Maximum 4,000 bytes.
`text`	string	Yes	-	The text to convert to speech. Supports markup tags like [sigh], [laughing], [whispering], [shouting], [extremely fast] for expressive delivery. Maximum 4,000 bytes.
`voice`	string	No	Kore	Voice to use for speech generation AchernarAchirdAlgenibAlgiebaAlnilamAoedeAutonoeCallirrhoeCharonDespinaEnceladusErinomeFenrirGacruxIapetusKoreLaomedeiaLedaOrusPulcherrimaPuckRasalgethiSadachbiaSadaltagerSchedarSulafatUmbrielVindemiatrixZephyrZubenelgenubi
`language_code`	string	No	en-US	Language for the speech output af-ZAam-ETar-001ar-EGaz-AZbe-BYbg-BGbn-BDca-ESceb-PHcmn-CNcmn-twcs-CZda-DKde-DEel-GRen-AUen-GBen-INen-USes-419es-ESes-MXet-EEeu-ESfa-IRfi-FIfil-PHfr-CAfr-FRgl-ESgu-INhe-ILhi-INhr-HRht-HThu-HUhy-AMid-IDis-ISit-ITja-JPjv-JVka-GEkn-INko-KRkok-INla-VAlb-LUlo-LAlt-LTlv-LVmai-INmg-MGmk-MKml-INmn-MNmr-INms-MYmy-MMnb-NOne-NPnl-NLnn-NOor-INpa-INpl-PLps-AFpt-BRpt-PTro-ROru-RUsd-INsi-LKsk-SKsl-SIsq-ALsr-RSsv-SEsw-KEta-INte-INth-THtr-TRuk-UAur-PKvi-VN

Common Parameters

Common parameters used when calling POST /v1/predictions.

Parameter	Type	Required	Default	Description
`model`	string	Yes	-	Model identifier
`input`	object	Yes	-	Object containing the model-specific parameters from the table above
`output_folder`	string	No	-	Folder path for output files (max 256 chars, '..' not allowed)
`webhook_url`	string	No	-	Webhook URL to call on completion
`is_public`	boolean	No	false	If true, output files are also available via permanent public URLs

Examples

Korean narration with style direction

Narrates Korean text in a calm, professional tone using the Kore voice.

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "google/gemini-3.1-flash-tts",
  "input": {
    "prompt": "Say this in a calm, professional tone, like a documentary narrator.",
    "text": "오늘 소개할 제품은 최신 무선 이어폰입니다. 뛰어난 음질과 편안한 착용감을 동시에 제공합니다.",
    "voice": "Kore",
    "language_code": "ko-KR"
  }
}'

Expressive English delivery with markup tags

Uses inline markup tags for an excited, expressive delivery in English.

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "google/gemini-3.1-flash-tts",
  "input": {
    "prompt": "Speak with excitement and energy, like announcing a big surprise.",
    "text": "[laughing] You won't believe this offer — it's fifty percent off, today only! [extremely fast] Don't miss out!",
    "voice": "Puck",
    "language_code": "en-US"
  }
}'