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TTS 1.5 Max

Text-to-Speech • Inworld • Proxied

Highest-quality text-to-speech with under 200ms latency, emotion control, and 15-language support.

Model Info
Terms and Licenselink ↗
More informationlink ↗

Usage

TypeScript
const response = await env.AI.run(
  'inworld/tts-1.5-max',
  {
    text: 'Hello! Welcome to Cloudflare AI Gateway. Let me show you what we can do.',
  },
  {
    gateway: { id: 'default' },
  }
)
console.log(response)
Response 200

Examples

Slow Narration — Slower speech for narration
TypeScript
const response = await env.AI.run(
  'inworld/tts-1.5-max',
  {
    text: 'In the beginning, the universe was a singularity of infinite density. Then, in a fraction of a second, it expanded into everything we know today.',
    speaking_rate: 0.85,
  },
  {
    gateway: { id: 'default' },
  }
)
console.log(response)
Response 200
High Quality Audio — Higher sample rate for studio quality
TypeScript
const response = await env.AI.run(
  'inworld/tts-1.5-max',
  {
    text: 'This recording is generated at studio quality for the best possible listening experience.',
    sample_rate: 48000,
  },
  {
    gateway: { id: 'default' },
  }
)
console.log(response)
Response 200
With Text Normalization — Expand numbers and abbreviations before synthesis
TypeScript
const response = await env.AI.run(
  'inworld/tts-1.5-max',
  {
    text: 'The meeting is at 3:30 PM on Jan 15th, 2026. Please confirm by calling 555-0123.',
    apply_text_normalization: true,
  },
  {
    gateway: { id: 'default' },
  }
)
console.log(response)
Response 200

Parameters

text
stringrequiredmaxLength: 2000The text to be synthesized into speech. Maximum input of 2,000 characters.
voice_id
stringdefault: Dennisenum: Loretta, Darlene, Marlene, Hank, Evelyn, Celeste, Pippa, Tessa, Liam, Callum, Hamish, Abby, Graham, Rupert, Mortimer, Snik, Anjali, Saanvi, Arjun, Claire, Oliver, Simon, Elliot, James, Serena, Gareth, Vinny, Lauren, Jessica, Ethan, Tyler, Jason, Chloe, Veronica, Victoria, Miranda, Sebastian, Victor, Malcolm, Nate, Brian, Amina, Kelsey, Derek, Evan, Kayla, Jake, Grant, Tristan, Nadia, Selene, Marcus, Riley, Damon, Cedric, Mia, Naomi, Jonah, Levi, Avery, Brandon, Conrad, Bianca, Lucian, Trevor, Alex, Ashley, Craig, Deborah, Dennis, Edward, Elizabeth, Hades, Julia, Pixie, Mark, Olivia, Priya, Ronald, Sarah, Shaun, Theodore, Timothy, Wendy, Dominus, Hana, Clive, Carter, Blake, Luna, Reed, Duncan, Felix, Eleanor, SophieThe ID of the voice to use for synthesizing speech. Defaults to Dennis.
output_format
stringdefault: mp3enum: mp3, opus, wav, flacThe output format for the audio. Supported formats are mp3, opus, wav, and flac. Defaults to mp3.
bit_rate
integerminimum: 0Bits per second of the audio. Only for compressed audio formats (mp3, opus). The default is 128,000.
sample_rate
integerenum: 8000, 16000, 22050, 24000, 32000, 44100, 48000The synthesis sample rate in hertz. Accepts: 8000, 16000, 22050, 24000, 32000, 44100, 48000. The default is 48,000.
speaking_rate
numberminimum: 0.5maximum: 1.5Speaking rate/speed, in the range [0.5, 1.5]. The default is 1.0. We recommend using values above 0.8 to ensure high quality.
temperature
numberdefault: 1minimum: 0.01maximum: 2Determines the degree of randomness when sampling audio tokens. Defaults to 1.0. Accepts values between 0 (exclusive) and 2 (inclusive). Higher values = more expressive, lower values = more deterministic.
timestamp_type
stringdefault: noneenum: none, word, characterControls timestamp metadata returned with the audio. "word" returns word-level timing, "character" returns character-level timing. Note: adds latency. Defaults to none.
apply_text_normalization
booleanWhen enabled, text normalization expands numbers, dates, times, and abbreviations before converting to speech. Turning this off may reduce latency.

API Schemas

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "text": {
      "description": "The text to be synthesized into speech. Maximum input of 2,000 characters.",
      "type": "string",
      "maxLength": 2000
    },
    "voice_id": {
      "description": "The ID of the voice to use for synthesizing speech. Defaults to Dennis.",
      "default": "Dennis",
      "type": "string",
      "enum": [
        "Loretta",
        "Darlene",
        "Marlene",
        "Hank",
        "Evelyn",
        "Celeste",
        "Pippa",
        "Tessa",
        "Liam",
        "Callum",
        "Hamish",
        "Abby",
        "Graham",
        "Rupert",
        "Mortimer",
        "Snik",
        "Anjali",
        "Saanvi",
        "Arjun",
        "Claire",
        "Oliver",
        "Simon",
        "Elliot",
        "James",
        "Serena",
        "Gareth",
        "Vinny",
        "Lauren",
        "Jessica",
        "Ethan",
        "Tyler",
        "Jason",
        "Chloe",
        "Veronica",
        "Victoria",
        "Miranda",
        "Sebastian",
        "Victor",
        "Malcolm",
        "Nate",
        "Brian",
        "Amina",
        "Kelsey",
        "Derek",
        "Evan",
        "Kayla",
        "Jake",
        "Grant",
        "Tristan",
        "Nadia",
        "Selene",
        "Marcus",
        "Riley",
        "Damon",
        "Cedric",
        "Mia",
        "Naomi",
        "Jonah",
        "Levi",
        "Avery",
        "Brandon",
        "Conrad",
        "Bianca",
        "Lucian",
        "Trevor",
        "Alex",
        "Ashley",
        "Craig",
        "Deborah",
        "Dennis",
        "Edward",
        "Elizabeth",
        "Hades",
        "Julia",
        "Pixie",
        "Mark",
        "Olivia",
        "Priya",
        "Ronald",
        "Sarah",
        "Shaun",
        "Theodore",
        "Timothy",
        "Wendy",
        "Dominus",
        "Hana",
        "Clive",
        "Carter",
        "Blake",
        "Luna",
        "Reed",
        "Duncan",
        "Felix",
        "Eleanor",
        "Sophie"
      ]
    },
    "output_format": {
      "description": "The output format for the audio. Supported formats are mp3, opus, wav, and flac. Defaults to mp3.",
      "default": "mp3",
      "type": "string",
      "enum": [
        "mp3",
        "opus",
        "wav",
        "flac"
      ]
    },
    "bit_rate": {
      "description": "Bits per second of the audio. Only for compressed audio formats (mp3, opus). The default is 128,000.",
      "type": "integer",
      "minimum": 0
    },
    "sample_rate": {
      "description": "The synthesis sample rate in hertz. Accepts: 8000, 16000, 22050, 24000, 32000, 44100, 48000. The default is 48,000.",
      "type": "integer",
      "enum": [
        8000,
        16000,
        22050,
        24000,
        32000,
        44100,
        48000
      ]
    },
    "speaking_rate": {
      "description": "Speaking rate/speed, in the range [0.5, 1.5]. The default is 1.0. We recommend using values above 0.8 to ensure high quality.",
      "type": "number",
      "minimum": 0.5,
      "maximum": 1.5
    },
    "temperature": {
      "description": "Determines the degree of randomness when sampling audio tokens. Defaults to 1.0. Accepts values between 0 (exclusive) and 2 (inclusive). Higher values = more expressive, lower values = more deterministic.",
      "default": 1,
      "type": "number",
      "minimum": 0.01,
      "maximum": 2
    },
    "timestamp_type": {
      "description": "Controls timestamp metadata returned with the audio. \"word\" returns word-level timing, \"character\" returns character-level timing. Note: adds latency. Defaults to none.",
      "default": "none",
      "type": "string",
      "enum": [
        "none",
        "word",
        "character"
      ]
    },
    "apply_text_normalization": {
      "description": "When enabled, text normalization expands numbers, dates, times, and abbreviations before converting to speech. Turning this off may reduce latency.",
      "type": "boolean"
    }
  },
  "required": [
    "text"
  ],
  "additionalProperties": false
}