API ReferenceText-to-Speech ModelsHeyGen
HeyGen Voice Turbo
HeyGen Voice Turbo — the same voices tuned for speed and volume, available on all plans.
The same HeyGen voices tuned for speed and volume, at half the price of HeyGen Voice. Available on every plan, including Free.
| Endpoint | POST /api/v1/tts/synthesize |
Model ID (ttsModel) | heygen-voice-turbo |
| Provider | HeyGen (Free + paid) |
| Character Limit | 5,000 (Free plan: 1,000) |
| Cost | 500 / 1K chars |
Shared conventions
Auth, the voice→provider rule, rate limits, and the full error table live on the Speech API page. Below is only what's specific to HeyGen Voice Turbo.
Model-specific notes
- Works on every plan, including Free (Free is capped at 1,000 chars/request).
- 24 voices, each speaking 39 languages. List them with GET /api/v1/tts/voices?provider=heygen; a voice is not tied to one language.
- Pick the spoken language with
language_code. When you leave it out, the language is detected from the text. - Output is MP3.
speed,pitchand the ElevenLabs voice settings are not supported and are ignored.
Supported language_code values: ar, be, bg, ca, cs, da, de, el, en, es, fa, fi, fr, he, hi, hr, hu, id, it, ja, ko, mk, ms, nl, pl, pt, ro, ru, sk, sl, sr, sv, ta, th, tl, tr, uk, vi, zh.
Request body
| Parameter | Type | Required | Description |
|---|---|---|---|
text | string | Yes | Text to synthesize (max 5,000 chars) |
voice | string | Yes | A HeyGen voice ID from GET /api/v1/tts/voices?provider=heygen |
ttsModel | string | Yes | Must be "heygen-voice-turbo" |
language_code | string | No | Spoken language, one of the codes above · Default: detected from the text |
title | string | No | Title for the saved project |
{
"text": "Welcome to SonnaLabs. Your audio is ready to download.",
"voice": "voice-uuid-heygen",
"ttsModel": "heygen-voice-turbo",
"language_code": "en"
}Response (200 OK)
{
"url": "https://cdn.sonnalabs.app/sonna/api-ephemeral/tts/paid/user123/pqr678.mp3",
"remainingCredits": 9850,
"projectCreated": true
}Errors (400 TEXT_TOO_LONG — 5,000, or 1,000 on Free — plus 402, 409, 429, 503) follow the shared Speech API table. No 403: HeyGen Voice Turbo is available to everyone.