ResourcesIntegrationsVoices (Text-to-speech)

Inworld

Use Inworld text-to-speech voices with your Vapi voice agent.

Inworld provides streaming text-to-speech voices that you can use as a Vapi assistant’s voice.

You can use Inworld through Vapi’s default integration, or use your own Inworld account by connecting it in Integrations.

Text-to-speech

Set voice.provider to inworld, voice.model to a supported model, and voice.voiceId to a voice. Inworld offers many voices; browse and copy a voice’s ID from the Voice Library.

$curl -X PATCH "https://api.vapi.ai/assistant/ASSISTANT_ID" \
>  -H "Authorization: Bearer $VAPI_API_KEY" \
>  -H "Content-Type: application/json" \
>  -d '{
>    "voice": {
>      "provider": "inworld",
>      "model": "inworld-tts-1.5-mini",
>      "voiceId": "Alex",
>      "languageCode": "en"
>    }
>  }'

For additional API configuration options, review the InworldVoice fields in the Create Assistant API reference.

Supported models

The following non-deprecated Inworld model IDs are supported by Vapi. See Inworld’s model catalog for provider details.

ModelModel ID
Realtime TTS 1.5 Maxinworld-tts-1.5-max
Realtime TTS 1.5 Miniinworld-tts-1.5-mini
Realtime TTS-2inworld-tts-2

Configuration options

OptionAccepted valuesDescription
voiceIdInworld voice IDSelects an Inworld voice.
modelSupported model IDSelects the text-to-speech model.
languageCodeSupported language codeSelects the synthesis language. The default is en.
temperature0.1 to 2Controls output variance. The default is 1.1.
speakingRate0.5 to 1.5Controls speaking speed. The default is 1.

Supported languages

Set voice.languageCode to one of the language codes below. Although Inworld offers additional language coverage for Realtime TTS-2, this table lists the languages currently accepted by Vapi.

LanguageLanguage codeRealtime TTS 1.5 MaxRealtime TTS 1.5 MiniRealtime TTS-2
ArabicarXXX
ChinesezhXXX
DutchnlXXX
EnglishenXXX
FrenchfrXXX
GermandeXXX
HebrewheXXX
HindihiXXX
ItalianitXXX
JapanesejaXXX
KoreankoXXX
PolishplXXX
PortugueseptXXX
RussianruXXX
SpanishesXXX
Voices

Compare every text-to-speech provider Vapi supports.