InworldFastHigh

Inworld Realtime TTS 2

Inworld's most expressive TTS with natural-language steering — place bracketed instructions like [speak quickly] before the text they apply to. Real-time latency and 15+ language support.

59 credits

per 1000 characters (0.057 credits/char, billed per character)

Natural-language steering with bracketed instructions

Real-time latency

15+ language support with auto detection

Preset voices or custom cloned voice IDs

Text normalization control for numbers and dates

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": "inworld/realtime-tts-2",
  "input": {
    "text": "[speak quickly with a clear and direct manner] Your confirmation number is 8 4 7 2 9. Your order will arrive by FRIDAY at 3:45 PM.",
    "voice_id": "Dennis",
    "audio_format": "mp3"
  }
}'

Parameters

Parameter	Type	Required	Default	Description
`text`	string	Yes	-	Text to convert (max 2,000 chars). Supports bracketed steering like [speak quickly] before the text it applies to
`voice_id`	string	No	Ashley	Preset voice name (Ashley, Dennis, Alex, Darlene) or a custom cloned voice ID
`language`	string	No	auto	Language of the input text. 'auto' detects automatically autoenzhjakoruitesptfrdeplnlhihear
`speaking_rate`	number	No	0	Speaking speed multiplier (0-1.5). 0 = normal speed (1.0)
`temperature`	number	No	0	Randomness control (0-2). 0 uses the model default
`audio_format`	string	No	mp3	Output audio format mp3wavogg_opusflac
`sample_rate`	integer	No	48000	Audio sample rate in Hz 8000160002205024000320004410048000
`text_normalization`	string	No	auto	Expand numbers/dates/abbreviations before synthesis autoonoff

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

Steered Delivery

Direct the speaking style with a bracketed instruction

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "inworld/realtime-tts-2",
  "input": {
    "text": "[speak quickly with a clear and direct manner] Your confirmation number is 8 4 7 2 9. Your order will arrive by FRIDAY at 3:45 PM.",
    "voice_id": "Dennis",
    "audio_format": "mp3"
  }
}'