Inworld AI
Text-to-Speech platform with voice cloning, audio markups, and timestamp alignment.
Quick Navigation
When to Use
- Text-to-speech audio generation
- Voice cloning from 5-15 seconds of audio
- Emotion-controlled speech (
[happy], [sad], etc.)
- Word/phoneme timestamps for lip sync
- Custom pronunciation with IPA
Models
| Model |
ID |
Latency |
Price |
| TTS-2 Flash |
inworld-tts-2-flash |
lowest |
see pricing |
| TTS-2 |
inworld-tts-2 |
latest |
see pricing |
| TTS 1.5 Max |
inworld-tts-1.5-max |
legacy |
legacy |
| TTS 1.5 Mini |
inworld-tts-1.5-mini |
legacy |
legacy |
Minimal Example
import requests, base64, os
response = requests.post(
"https://api.inworld.ai/tts/v1/voice",
headers={"Authorization": f"Basic {os.getenv('INWORLD_API_KEY')}"},
json={"text": "Hello!", "voiceId": "Ashley", "modelId": "inworld-tts-1.5-max"}
)
audio = base64.b64decode(response.json()['audioContent'])
Key Features
- 15 languages — en, zh, ja, ko, ru, it, es, pt, fr, de, pl, nl, hi, he, ar
- Instant cloning — 5-15 seconds audio, no training
- Audio markups —
[happy], [laughing], [sigh] (English only)
- Timestamps — word, phoneme, viseme timing for lip sync
- Streaming —
/voice:stream endpoint
- TTS-2 steering — natural-language bracketed directions such as
[say excitedly] or [whisper in a hushed style]
- Delivery mode —
STABLE, BALANCED, CREATIVE trade consistency for emotional range
- Cross-lingual synthesis — reuse one voice across multiple languages; voice localization improves native-sounding output
Release Highlights (TTS-2)
Realtime TTS-2 becomes the new primary model line via modelId="inworld-tts-2".- Steering moves beyond the older fixed emotion tags: free-form bracketed directions can control style, pitch, speed, intensity, and non-verbals.
- Multilingual coverage expands with production quality across 15 languages and broader experimental coverage beyond that.
deliveryMode adds a stability-vs-creativity knob, and specifying language matters more for cross-lingual output quality.
Release Updates (August 2026)
- New
inworld-tts-2-flash model: lowest latency and cost, full language coverage, instant voice cloning, and timestamp alignment. Steering and Professional Voice Cloning remain exclusive to inworld-tts-2.
- Steering instructions now persist until explicitly changed: a reserved
[reset] tag ends a styled passage, and a <break/> pause no longer clears the active instruction. A request-level instruction field on Synthesize Speech is an alternative to inline tags.
- Cross-lingual voice synthesis and voice localization improve native-sounding output when one voice is reused across languages.
Prohibitions
- Audio markups work only in English
- Use ONE emotion markup at text beginning
- Match voice language to text language
- Instant cloning may not work for children's voices or unique accents
Links
