InworldFastHigh

Inworld TTS 1.5 Max

Inworld's highest-quality realtime TTS with under 200ms latency. Supports SSML break tags for pauses, emotion markups like [happy], and 15 languages.

24 credits

per 1000 characters (0.023 credits/char, billed per character)

Under 200ms median latency

Emotion markups: [happy], [sad], [angry]

SSML break tags for precise pauses

15 language support

Very low per-character price

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/tts-1.5-max",
  "input": {
    "text": "[happy] Welcome back! <break time=\"0.5s\" /> Your order shipped this morning and arrives tomorrow.",
    "voice_id": "Ashley"
  }
}'

Parameters

Parameter	Type	Required	Default	Description
`text`	string	Yes	-	Text to convert (max 2,000 chars). Supports SSML breaks (<break time="1s" />) and emotion markups like [happy], [sad]
`voice_id`	string	No	Ashley	Preset voice name (Ashley, Dennis, Alex, Darlene) or a custom cloned voice ID
`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

Emotion-Marked Assistant Reply

Happy greeting with a precise pause

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/tts-1.5-max",
  "input": {
    "text": "[happy] Welcome back! <break time=\"0.5s\" /> Your order shipped this morning and arrives tomorrow.",
    "voice_id": "Ashley"
  }
}'