MODEL ID inworld:tts@1.5-mini

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Inworld TTS-1.5 Mini

by Inworld AI January 21, 2026

Inworld TTS-1.5 Mini is a lightweight text-to-speech model designed for real-time voice experiences with ultra-low latency and efficient performance. It delivers natural, expressive audio suitable for interactive agents, voice assistants, and conversational applications where responsiveness is critical. The Mini variant balances speed and quality, enabling responsive speech output even under constrained compute conditions.

API Options

Platform-level options for task execution and delivery.

taskType string required value: audioInference: Identifier for the type of task being performed

taskUUID string required UUID v4: UUID v4 identifier for tracking tasks and matching async responses. Must be unique per task.

outputType string default: URL: Audio output type.

Allowed values 3 values

outputFormat string default: MP3

Specifies the file format of the generated output. The available values depend on the task type and the specific model's capabilities.

`MP3`: Compressed audio, smaller file size.
`WAV`: Uncompressed, high-quality audio.
`FLAC`: Lossless compression.
`OGG`: Open-source compressed audio format (Vorbis codec).

Allowed values 4 values

webhookURL string URI

Specifies a webhook URL where JSON responses will be sent via HTTP POST when generation tasks complete. For batch requests with multiple results, each completed item triggers a separate webhook call as it becomes available.

Learn more 1 resource

Webhooks
PLATFORM

deliveryMethod string default: sync

Determines how the API delivers task results.

Allowed values 2 values

: Returns complete results directly in the API response.
: Returns an immediate acknowledgment with the task UUID. Poll for results using getResponse.

Learn more 1 resource

Task Polling
PLATFORM

uploadEndpoint string URI

Specifies a URL where the generated content will be automatically uploaded using the HTTP PUT method. The raw binary data of the media file is sent directly as the request body. For secure uploads to cloud storage, use presigned URLs that include temporary authentication credentials.

Common use cases:

Cloud storage: Upload directly to S3 buckets, Google Cloud Storage, or Azure Blob Storage using presigned URLs.
CDN integration: Upload to content delivery networks for immediate distribution.

// S3 presigned URL for secure upload
https://your-bucket.s3.amazonaws.com/generated/content.mp4?X-Amz-Signature=abc123&X-Amz-Expires=3600

// Google Cloud Storage presigned URL
https://storage.googleapis.com/your-bucket/content.jpg?X-Goog-Signature=xyz789

// Custom storage endpoint
https://storage.example.com/uploads/generated-image.jpg

The content data will be sent as the request body to the specified URL when generation is complete.

ttl integer min: 60: Time-to-live (TTL) in seconds for generated content. Only applies when outputType is URL.

includeCost boolean default: false: Include task cost in the response.

numberResults integer min: 1 max: 4 default: 1: Number of results to generate. Each result uses a different seed, producing variations of the same parameters.

Generation Parameters

Core parameters for controlling the generated content.

audioSettings object

Advanced settings for audio generation.

Properties 3 properties

audioSettings » bitrate bitrate integer min: 1: Target audio bitrate in kbps. Constraints depend on the output format.

audioSettings » sampleRate sampleRate integer min: 1000: Audio sample rate in Hz.

audioSettings » channels channels integer default: 2: Number of audio channels in the generated output (1 for Mono, 2 for Stereo).

Allowed values 2 values

model string required value: inworld:tts@1.5-mini

Identifier of the model to use for generation.

Learn more 3 resources

speech object required

Settings for speech generation.

Properties 3 properties

speech » text text string required min: 2 max: 2000: Text to convert to speech.

speech » voice voice string required default: auto: Voice identifier to use. Set to auto for automatic selection.

Allowed values 73 values

speech » speed speed float min: 0.5 max: 1.5 step: 0.1 default: 1: Playback speed of the generated speech.

Settings

Technical parameters to fine-tune the inference process. These must be nested inside the settings object.

settings » temperature temperature float min: 0.1 max: 2 step: 0.01 default: 1.1: Controls randomness in generation. Lower values produce more deterministic outputs, higher values increase variation and creativity.

taskType string required value: audioInference: Type of the task.

taskUUID string required UUID v4: UUID of the task.

audioUUID string required UUID v4: UUID of the output audio.

audioURL string URI: URL of the output audio.

audioBase64Data string: Base64-encoded audio data.

audioDataURI string URI: Data URI of the output audio.

seed integer: The seed used for generation. If none was provided, shows the randomly generated seed.

cost float: Task cost in USD. Present when includeCost is set to true in the request.

Text to Audio

Submersible Wake-Up Announcement Sequence

0:00

Request

{
  "taskType": "audioInference",
  "taskUUID": "2779b408-2342-4139-a86c-e50277e40225",
  "model": "inworld:tts@1.5-mini",
  "audioSettings": {
    "bitrate": 128,
    "sampleRate": 24000,
    "channels": 2
  },
  "speech": {
    "text": "Good morning, crew. Depth is stable at three hundred twenty meters, external pressure remains within expected range, and all survey drones have returned to dock. Breakfast service begins in ten minutes in the galley. Before deployment, please confirm suit seals, update your dive slates, and report any equipment faults to navigation. Today’s route passes through a field of glass sponges and narrow basalt arches, so maintain line-of-sight with your team at all times. Have a steady shift.",
    "voice": "Claire",
    "speed": 1
  },
  "settings": {
    "temperature": 0.72
  }
}

Response

{
  "taskType": "audioInference",
  "taskUUID": "2779b408-2342-4139-a86c-e50277e40225",
  "audioUUID": "3c8c5a54-21ea-47f6-8eaa-1573d90aed35",
  "audioURL": "https://am.runware.ai/audio/os/a10d08/ws/5/ai/3c8c5a54-21ea-47f6-8eaa-1573d90aed35.mp3",
  "cost": 0.00245
}

Text to Audio

Antique Museum Closing Announcement

0:00

Request

{
  "taskType": "audioInference",
  "taskUUID": "c6f4bca6-9b03-4f04-b18f-35f2bea66c03",
  "model": "inworld:tts@1.5-mini",
  "audioSettings": {
    "bitrate": 128,
    "sampleRate": 44100,
    "channels": 2
  },
  "speech": {
    "text": "Good evening, guests. The Hall of Maritime Relics will close in fifteen minutes. Please make your way toward the east atrium and keep all hands clear of the restoration platforms. Our conservators will begin nightly preservation work shortly, including low-light scans of the copper astrolabes and the cedar navigation chest recovered from the Barrow Strait expedition. If you are waiting for the final guided viewing of the storm log exhibit, please gather beside the blue banner near Gallery Three. Thank you for spending your evening with us, and we wish you a safe journey home.",
    "voice": "Graham",
    "speed": 1
  },
  "settings": {
    "temperature": 0.72
  }
}

Response

{
  "taskType": "audioInference",
  "taskUUID": "c6f4bca6-9b03-4f04-b18f-35f2bea66c03",
  "audioUUID": "51ce40f9-3a8a-40b5-bbfb-e03b0f42ac74",
  "audioURL": "https://am.runware.ai/audio/os/a25d05/ws/5/ai/51ce40f9-3a8a-40b5-bbfb-e03b0f42ac74.mp3",
  "cost": 0.00291
}

Text to Audio

Orbital Greenhouse Emergency Bulletin

0:00

Request

{
  "taskType": "audioInference",
  "taskUUID": "8b0efad2-26ac-49f6-b307-73d84fd703b8",
  "model": "inworld:tts@1.5-mini",
  "audioSettings": {
    "bitrate": 128,
    "sampleRate": 44100,
    "channels": 2
  },
  "speech": {
    "text": "Attention all greenhouse crews. This is a station systems bulletin for Ring B. A pressure imbalance has been detected in pollination corridor three. Please secure loose equipment, pause all drone activity, and move to the nearest sealed junction. Oxygen levels remain stable, and there is no fire risk at this time. Maintenance teams are already responding. If you are carrying seed vault trays, leave them on the nearest rack and proceed calmly. Repeat: pressure imbalance, Ring B, pollination corridor three. Follow amber floor guidance and await further instructions.",
    "voice": "Claire",
    "speed": 1
  },
  "settings": {
    "temperature": 0.72
  }
}

Response

{
  "taskType": "audioInference",
  "taskUUID": "8b0efad2-26ac-49f6-b307-73d84fd703b8",
  "audioUUID": "722f687f-51dc-42e8-8960-db415627f6ed",
  "audioURL": "https://am.runware.ai/audio/os/a23d05/ws/5/ai/722f687f-51dc-42e8-8960-db415627f6ed.mp3",
  "cost": 0.00285
}

Text to Audio

Glacier Tram Arrival Advisory

0:00

Request

{
  "taskType": "audioInference",
  "taskUUID": "e0024d1f-07d9-43ac-a814-65239f21dde0",
  "model": "inworld:tts@1.5-mini",
  "audioSettings": {
    "bitrate": 128,
    "sampleRate": 44100,
    "channels": 2
  },
  "speech": {
    "text": "Attention passengers on the North Ice Tram. Due to high crosswinds over Span Four, arrival at Frost Hollow Station will be delayed by approximately six minutes. Please remain behind the blue safety line until the cabin comes to a complete stop. Connecting shuttle sleds to Upper Ridge will wait for all ticketed riders. Climbers transferring with gear should use the rear loading platform. Thank you for your patience, and enjoy the view across the glacier basin.",
    "voice": "Claire",
    "speed": 1
  },
  "settings": {
    "temperature": 0.78
  }
}

Response

{
  "taskType": "audioInference",
  "taskUUID": "e0024d1f-07d9-43ac-a814-65239f21dde0",
  "audioUUID": "a0dfe4d1-d5dc-47c1-84ac-dc3f2852cc8c",
  "audioURL": "https://am.runware.ai/audio/os/a18d05/ws/5/ai/a0dfe4d1-d5dc-47c1-84ac-dc3f2852cc8c.mp3",
  "cost": 0.00232
}