--- description: Gemini 3.8 Flash TTS is Google's flagship text-to-speech model for expressive, natural speech generation. title: Gemini 3.8 Flash TTS image: https://developers.cloudflare.com/og-docs.png --- [Skip to content](#main-content) > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/llms.txt > Use this file to discover all available pages before exploring further. ![Google logo](https://developers.cloudflare.com/_astro/google.DyXKPTPP.svg) # Gemini 3.8 Flash TTS Text-to-Speech • Google Copy as Markdown| [View as Markdown](https://developers.cloudflare.com/ai/models/google/gemini-3.8-flash-tts/index.md)| [Agent setup](https://developers.cloudflare.com/agent-setup/) Model ID `google/gemini-3.8-flash-tts` Copy Use with the [Workers AI binding](https://developers.cloudflare.com/ai-gateway/usage/worker-binding-methods/), the AI Gateway [REST API](https://developers.cloudflare.com/ai-gateway/usage/rest-api/), or the [Unified API](https://developers.cloudflare.com/ai-gateway/usage/chat-completion/). Calling the provider directly? Use the provider's model name instead, including with [provider-native endpoints](https://developers.cloudflare.com/ai-gateway/usage/providers/) or the provider's own SDK. For example, Anthropic's name for `anthropic/claude-opus-4.8` is `claude-opus-4-8`. - Third-party Gemini 3.8 Flash TTS is Google's flagship text-to-speech model for expressive, natural speech generation. | Model Info | | | --- | --- | | Context Window [ ↗](https://developers.cloudflare.com/workers-ai/platform/glossary/) | 8,192 tokens | | More information | [link ↗](https://ai.google.dev/gemini-api/docs/models/gemini-3.8-flash-tts) | | Pricing | | ## Usage ```ts const response = await env.AI.run( 'google/gemini-3.8-flash-tts', { text: 'Hello, welcome to Cloudflare AI Gateway!' }, ) console.log(response) ``` ```bash curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "google/gemini-3.8-flash-tts", "input": { "text": "Hello, welcome to Cloudflare AI Gateway!" } }' ``` ```json { "audio": "https://examples.aig.cloudflare.com/google/gemini-3.8-flash-tts/simple-text-to-speech.wav", "gatewayMetadata": { "keySource": "Unified" } } ``` ## Examples
**Expressive Pause** — Generate expressive speech with an inline vocal pause ```ts const response = await env.AI.run( 'google/gemini-3.8-flash-tts', { text: 'Welcome to the future of voice. Let us build something remarkable together.', voice: 'Puck', }, ) console.log(response) ``` ```bash curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "google/gemini-3.8-flash-tts", "input": { "text": "Welcome to the future of voice. Let us build something remarkable together.", "voice": "Puck" } }' ``` ```json { "audio": "https://examples.aig.cloudflare.com/google/gemini-3.8-flash-tts/expressive-pause.wav", "gatewayMetadata": { "keySource": "Unified" } } ```
**Narrated Passage** — Generate a longer narrated passage with a different voice ```ts const response = await env.AI.run( 'google/gemini-3.8-flash-tts', { text: 'At sunrise, the research team opened the observatory and watched the first light move across the valley. Every sensor came online in sequence, and the quiet room filled with the soft rhythm of discovery.', voice: 'Charon', }, ) console.log(response) ``` ```bash curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "google/gemini-3.8-flash-tts", "input": { "text": "At sunrise, the research team opened the observatory and watched the first light move across the valley. Every sensor came online in sequence, and the quiet room filled with the soft rhythm of discovery.", "voice": "Charon" } }' ``` ```json { "audio": "https://examples.aig.cloudflare.com/google/gemini-3.8-flash-tts/narrated-passage.wav", "gatewayMetadata": { "keySource": "Unified" } } ```
**French Greeting** — Generate speech from a French greeting using a distinct voice ```ts const response = await env.AI.run( 'google/gemini-3.8-flash-tts', { text: "Bonjour et bienvenue. Nous sommes ravis de vous accompagner aujourd'hui.", voice: 'Kore', }, ) console.log(response) ``` ```bash curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "google/gemini-3.8-flash-tts", "input": { "text": "Bonjour et bienvenue. Nous sommes ravis de vous accompagner aujourd'\''hui.", "voice": "Kore" } }' ``` ```json { "audio": "https://examples.aig.cloudflare.com/google/gemini-3.8-flash-tts/french-greeting.wav", "gatewayMetadata": { "keySource": "Unified" } } ```
## Parameters text `string`requiredmaxLength: 10000The text to convert to speech. Maximum 10,000 characters. voice `string`enum: Zephyr, Puck, Charon, Kore, Fenrir, Leda, Orus, Aoede, Callirrhoe, Autonoe, Enceladus, Iapetus, Umbriel, Algieba, Despina, Erinome, Algenib, Rasalgethi, Laomedeia, Achernar, Alnilam, Schedar, Gacrux, Pulcherrima, Achird, Zubenelgenubi, Vindemiatrix, Sadachbia, Sadaltager, SulafatThe voice to use for speech synthesis temperature `number`minimum: 0maximum: 2Controls randomness in generation (0-2) topP `number`minimum: 0maximum: 1Nucleus sampling threshold (0-1). Tokens with cumulative probability up to topP are considered topK `integer`exclusiveMinimum: 0maximum: 9007199254740991Only sample from the top K tokens. Smaller K = more focused, larger K = more diverse maxOutputTokens `integer`exclusiveMinimum: 0maximum: 9007199254740991Maximum number of tokens to generate ▶stopSequences\[] `array`Sequences where the model will stop generating further tokens audio `string`Base64-encoded audio data (WAV format) ## API Schemas (Raw) Input [Open](https://developers.cloudflare.com/ai/models/google/gemini-3.8-flash-tts/schema-input.json) [Download](https://developers.cloudflare.com/ai/models/google/gemini-3.8-flash-tts/schema-input.json) Output [Open](https://developers.cloudflare.com/ai/models/google/gemini-3.8-flash-tts/schema-output.json) [Download](https://developers.cloudflare.com/ai/models/google/gemini-3.8-flash-tts/schema-output.json) Was this helpful? YesNo ## On this page [![](https://developers.cloudflare.com/_astro/logo.te5VL_aD.svg)Docs](https://developers.cloudflare.com/) ```json {"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/ai/models/google/gemini-3.8-flash-tts/#page","headline":"Gemini 3.8 Flash TTS","description":"Gemini 3.8 Flash TTS is Google's flagship text-to-speech model for expressive, natural speech generation.","url":"https://developers.cloudflare.com/ai/models/google/gemini-3.8-flash-tts/","inLanguage":"en","image":"https://developers.cloudflare.com/og-docs.png","publisher":{"@type":"Organization","name":"Cloudflare","description":"One platform for your apps, agents, and workforce. Build, secure, and scale without managing infrastructure","url":"https://www.cloudflare.com/","sameAs":["https://github.com/cloudflare","https://www.linkedin.com/company/cloudflare","https://x.com/cloudflare"],"logo":{"@type":"ImageObject","url":"https://developers.cloudflare.com/logo.svg"},"address":{"@type":"PostalAddress","streetAddress":"101 Townsend St","addressLocality":"San Francisco","addressRegion":"CA","postalCode":"94107","addressCountry":"US"},"contactPoint":[{"@type":"ContactPoint","contactType":"Customer Support","url":"https://support.cloudflare.com/","availableLanguage":["English"]},{"@type":"ContactPoint","contactType":"Sales","url":"https://www.cloudflare.com/contact/","availableLanguage":["English"]}]},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}} ```