Generate expressive speech with Gemini 3.8 Flash Lite TTS. Choose from 30 voices, guide delivery with style instructions, and create single-speaker narration or two-speaker dialogue.

google/gemini-3.8-flash-lite-tts

Generate expressive speech with Gemini 3.8 Flash Lite TTS. Choose from 30 voices, guide delivery with style instructions, and create single-speaker narration or two-speaker dialogue.

Inference

Commercial use

Partner

Schema

LLMs

Playground API

google/gemini-3.8-flash-lite-tts

Schema

Generate expressive speech with Gemini 3.8 Flash Lite TTS. Choose from 30 voices, guide delivery with style instructions, and create single-speaker narration or two-speaker dialogue.

google/gemini-3.8-flash-lite-tts

Generate expressive speech with Gemini 3.8 Flash Lite TTS. Choose from 30 voices, guide delivery with style instructions, and create single-speaker narration or two-speaker dialogue.

Inference

Commercial use

Partner

Schema

LLMs

Playground API

About

Text To Speech

1. Calling the API#

Install the client#

The client provides a convenient way to interact with the model API.

npm install --save @fal-ai/client

Migrate to @fal-ai/client

The @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.

Setup your API Key#

Set FAL_KEY as an environment variable in your runtime.

export FAL_KEY="YOUR_API_KEY"

Submit a request#

The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.

import { fal } from "@fal-ai/client";

const result = await fal.subscribe("google/gemini-3.8-flash-lite-tts", {
  input: {},
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});
console.log(result.data);
console.log(result.requestId);

2. Authentication#

The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.

API Key#

In an environment where you cannot set environment variables, you can configure the API key manually on the client.

import { fal } from "@fal-ai/client";

fal.config({
  credentials: "YOUR_FAL_KEY"
});

Protect your API Key

When running code on the client-side (e.g. in a browser, mobile app or GUI applications), make sure to not expose your FAL_KEY. Instead, use a server-side proxy to make requests to the API. For more information, check out our server-side integration guide.

3. Queue#

Long-running requests

For long-running requests, such as training jobs or models with slower inference times, it is recommended to check the Queue status and rely on Webhooks instead of blocking while waiting for the result.

Submit a request#

The client API provides a convenient way to submit requests to the model.

import { fal } from "@fal-ai/client";

const { request_id } = await fal.queue.submit("google/gemini-3.8-flash-lite-tts", {
  input: {},
  webhookUrl: "https://optional.webhook.url/for/results",
});

Fetch request status#

You can fetch the status of a request to check if it is completed or still in progress.

import { fal } from "@fal-ai/client";

const status = await fal.queue.status("google/gemini-3.8-flash-lite-tts", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
  logs: true,
});

Get the result#

Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.

import { fal } from "@fal-ai/client";

const result = await fal.queue.result("google/gemini-3.8-flash-lite-tts", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);

4. Files#

Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.

Data URI (base64)#

You can pass a Base64 data URI as a file input. The API will handle the file decoding for you. Keep in mind that for large files, this alternative although convenient can impact the request performance.

Hosted files (URL)#

You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.

Uploading files#

We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.

import { fal } from "@fal-ai/client";

const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);

Auto uploads

The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).

Read more about file handling in our file upload guide.

5. Schema#

Input#

prompt string

Verbatim text for single-speaker speech. Put delivery directions in style_instructions; inline vocal events may use <laugh> or <sigh>. For dialogue, omit prompt and provide speakers and turns instead. The provider limits the complete input to 8,192 tokens.

style_instructions string

Delivery style, separate from the spoken transcript. Applies to all turns unless overridden.

voice VoiceEnum

Prebuilt voice for single-speaker speech. Default value: "Kore"

Possible enum 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

speakers list<SpeakerConfig>

Exactly two distinct speaker aliases and their prebuilt voices for dialogue.

turns list<SpeechTurn>

Ordered dialogue turns, each identifying a configured speaker.

enable_safety_checker boolean

Authorized callers may set false to request relaxed screening. Default value: true

{
  "prompt": "Have a wonderful day!",
  "style_instructions": "cheerful and friendly",
  "voice": "Kore",
  "speakers": null,
  "turns": null,
  "enable_safety_checker": true
}

Output#

audio File* required

Generated WAV audio.

{
  "audio": {
    "url": "",
    "content_type": "image/png",
    "file_name": "z9RV14K95DvU.png",
    "file_size": 4404019
  }
}

Other types#

File#

url string* required

The URL where the file can be downloaded from.

content_type string

The mime type of the file.

file_name string

The name of the file. It will be auto-generated if not provided.

file_size integer

The size of the file in bytes.

SpeechTurn#

speaker_id string* required

Alias of a configured speaker.

text string* required

Verbatim transcript for this turn.

style_instructions string

Optional delivery style for this turn.

SpeakerConfig#

speaker_id string* required

Speaker alias used in each turn.

voice VoiceEnum* required

Prebuilt voice for this speaker.

Related Models

1. Calling the API

2. Authentication

API Key

3. Queue

4. Files

5. Schema

About

Text To Speech

1. Calling the API#

Install the client#

The client provides a convenient way to interact with the model API.

npm install --save @fal-ai/client

Migrate to @fal-ai/client

The @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.

Setup your API Key#

Set FAL_KEY as an environment variable in your runtime.

export FAL_KEY="YOUR_API_KEY"

Submit a request#

The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.

import { fal } from "@fal-ai/client";

const result = await fal.subscribe("google/gemini-3.8-flash-lite-tts", {
  input: {},
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});
console.log(result.data);
console.log(result.requestId);

2. Authentication#

The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.

API Key#

In an environment where you cannot set environment variables, you can configure the API key manually on the client.

import { fal } from "@fal-ai/client";

fal.config({
  credentials: "YOUR_FAL_KEY"
});

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

The client API provides a convenient way to submit requests to the model.

import { fal } from "@fal-ai/client";

const { request_id } = await fal.queue.submit("google/gemini-3.8-flash-lite-tts", {
  input: {},
  webhookUrl: "https://optional.webhook.url/for/results",
});

Fetch request status#

You can fetch the status of a request to check if it is completed or still in progress.

import { fal } from "@fal-ai/client";

const status = await fal.queue.status("google/gemini-3.8-flash-lite-tts", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
  logs: true,
});

Get the result#

Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.

import { fal } from "@fal-ai/client";

const result = await fal.queue.result("google/gemini-3.8-flash-lite-tts", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);

4. Files#

Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.

Data URI (base64)#

Hosted files (URL)#

You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.

Uploading files#

We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.

import { fal } from "@fal-ai/client";

const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);

Auto uploads

The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).

Read more about file handling in our file upload guide.

5. Schema#

Input#

prompt string

style_instructions string

Delivery style, separate from the spoken transcript. Applies to all turns unless overridden.

voice VoiceEnum

Prebuilt voice for single-speaker speech. Default value: "Kore"

speakers list<SpeakerConfig>

Exactly two distinct speaker aliases and their prebuilt voices for dialogue.

turns list<SpeechTurn>

Ordered dialogue turns, each identifying a configured speaker.

enable_safety_checker boolean

Authorized callers may set false to request relaxed screening. Default value: true

{
  "prompt": "Have a wonderful day!",
  "style_instructions": "cheerful and friendly",
  "voice": "Kore",
  "speakers": null,
  "turns": null,
  "enable_safety_checker": true
}

Output#

audio File* required

Generated WAV audio.

{
  "audio": {
    "url": "",
    "content_type": "image/png",
    "file_name": "z9RV14K95DvU.png",
    "file_size": 4404019
  }
}

Other types#

File#

url string* required

The URL where the file can be downloaded from.

content_type string

The mime type of the file.

file_name string

The name of the file. It will be auto-generated if not provided.

file_size integer

The size of the file in bytes.

SpeechTurn#

speaker_id string* required

Alias of a configured speaker.

text string* required

Verbatim transcript for this turn.

style_instructions string

Optional delivery style for this turn.

SpeakerConfig#

speaker_id string* required

Speaker alias used in each turn.

voice VoiceEnum* required

Prebuilt voice for this speaker.

google/gemini-3.8-flash-lite-tts

Table of contents

Table of contents

google/gemini-3.8-flash-lite-tts

Table of contents

1. Calling the API

2. Authentication

3. Queue

4. Files

5. Schema

About

1. Calling the API#

Install the client#

Migrate to @fal-ai/client

Setup your API Key#

Submit a request#

2. Authentication#

API Key#

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

Fetch request status#

Get the result#

4. Files#

Data URI (base64)#

Hosted files (URL)#

Uploading files#

Auto uploads

5. Schema#

Input#

Output#

Other types#

File#

SpeechTurn#

SpeakerConfig#

Related Models

Table of contents

Table of contents

1. Calling the API

2. Authentication

3. Queue

4. Files

5. Schema

About

1. Calling the API#

Install the client#

Migrate to @fal-ai/client

Setup your API Key#

Submit a request#

2. Authentication#

API Key#

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

Fetch request status#

Get the result#

4. Files#

Data URI (base64)#

Hosted files (URL)#

Uploading files#

Auto uploads

5. Schema#

Input#

Output#

Other types#

File#

SpeechTurn#

SpeakerConfig#

Related Models