Models

Generate Speech

Generate speech from the voice identified by voice_id.

The request stays open until speech generation finishes. The response contains a URL to a 44.1 kHz mono WAV file.

Voice and settings

Use an ACTIVE HeyGen Voice clone in your workspace. heygen-voice-1-turbo speaks instant clones at lower latency and refuses professional clones. API-key billing accumulates fractional usage. OAuth requests, including MCP calls, are rounded up per request to whole billing units, so their effective cost can be higher.

seed, speed, pitch_shift, and pitch_variance apply only to professional clones. Instant clones, including Turbo, accept and ignore these controls.

Language

Set language to the language of text. If you omit it, the language is detected from text. Successful responses include Content-Language, the language the speech was generated in.

Limits and request ID

The rate limit is 30 requests per minute per workspace member.

Successful responses include X-Request-Id. Use this ID when you contact support about the request.

POST

models

audio

tts

Generate Speech

curl --request POST \
  --url https://api.heygen.com/v3/models/audio/tts \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "language": "en",
  "text": "Hello from HeyGen Voice.",
  "voice_id": "<voice_id>"
}
'

import requests

url = "https://api.heygen.com/v3/models/audio/tts"

payload = {
    "language": "en",
    "text": "Hello from HeyGen Voice.",
    "voice_id": "<voice_id>"
}
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({language: 'en', text: 'Hello from HeyGen Voice.', voice_id: '<voice_id>'})
};

fetch('https://api.heygen.com/v3/models/audio/tts', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.heygen.com/v3/models/audio/tts",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'language' => 'en',
    'text' => 'Hello from HeyGen Voice.',
    'voice_id' => '<voice_id>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.heygen.com/v3/models/audio/tts"

	payload := strings.NewReader("{\n  \"language\": \"en\",\n  \"text\": \"Hello from HeyGen Voice.\",\n  \"voice_id\": \"<voice_id>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("x-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.heygen.com/v3/models/audio/tts")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"language\": \"en\",\n  \"text\": \"Hello from HeyGen Voice.\",\n  \"voice_id\": \"<voice_id>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.heygen.com/v3/models/audio/tts")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"language\": \"en\",\n  \"text\": \"Hello from HeyGen Voice.\",\n  \"voice_id\": \"<voice_id>\"\n}"

response = http.request(request)
puts response.read_body

{
  "data": {
    "audio_url": "<string>",
    "duration": 1,
    "original_characters": [
      {
        "text": "<string>",
        "start_time": 1,
        "end_time": 1
      }
    ]
  }
}

Authorizations

x-api-key

string

header

required

HeyGen API key. Obtain from your HeyGen dashboard.

Body

application/json

voice_id

string

required

Identifier of the voice used for speech synthesis.

Minimum string length: 1

text

string

required

Plain text to synthesize. A professional voice clone takes pauses (seconds, up to 5 per pause, e.g. ); other SSML, and break tags for an instant voice clone, are not supported.

Required string length: 1 - 5000

model

enum<string>

default:heygen-voice-1

heygen-voice-1: instant and professional voices. heygen-voice-1-turbo: heygen-voice-1 instant voices only, at lower latency.

Available options:

heygen-voice-1,

heygen-voice-1-turbo

language

string | null

Language code of text. Regional tags normalize to their supported base language, such as en-US to en. Omit it to detect the language from text. A confident reading that matches the letters of text is used, and the request fails with invalid_parameter if HeyGen Voice does not speak that language. Otherwise the first of these that HeyGen Voice speaks is used: the language the voice was created in, if text is written in that language's script; a less certain reading that a second reading of text without its numbers and brand names agrees with; the usual language of the script text is mostly written in, such as English for Latin letters; and, only when that script has no usual language, the reading itself. If none of them applies, the request fails with invalid_parameter. The Content-Language response header names the language used.

Minimum string length: 1

expressiveness_boost

number

default:1

Expressiveness boost for instant voices on HeyGen Voice 1.0, from 0.0 to 1.0. Omit for professional voices.

Required range: 0 <= x <= 1

seed

integer | null

Optional best-effort deterministic generation seed for professional clones. Ignored for instant clones.

Required range: 0 <= x <= 4294967295

speed

number | null

Speech speed multiplier for professional clones. Ignored for instant clones, including Turbo.

Required range: 0.75 <= x <= 1.25

pitch_shift

number | null

Pitch shift in semitones for professional clones. Ignored for instant clones.

Required range: -4 <= x <= 4

pitch_variance

number | null

Pitch variation multiplier for professional clones; 1.0 preserves the voice default. Ignored for instant clones.

Required range: 0.5 <= x <= 2

with_timestamps

boolean

default:false

Whether to include original_characters in the response: the start and end time of each character of text.

Response

Successful response

data

CreateSpeechResponseData · object

Show child attributes

⌘I

Generate Speech

curl --request POST \
  --url https://api.heygen.com/v3/models/audio/tts \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "language": "en",
  "text": "Hello from HeyGen Voice.",
  "voice_id": "<voice_id>"
}
'

import requests

url = "https://api.heygen.com/v3/models/audio/tts"

payload = {
    "language": "en",
    "text": "Hello from HeyGen Voice.",
    "voice_id": "<voice_id>"
}
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({language: 'en', text: 'Hello from HeyGen Voice.', voice_id: '<voice_id>'})
};

fetch('https://api.heygen.com/v3/models/audio/tts', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.heygen.com/v3/models/audio/tts",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'language' => 'en',
    'text' => 'Hello from HeyGen Voice.',
    'voice_id' => '<voice_id>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.heygen.com/v3/models/audio/tts"

	payload := strings.NewReader("{\n  \"language\": \"en\",\n  \"text\": \"Hello from HeyGen Voice.\",\n  \"voice_id\": \"<voice_id>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("x-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.heygen.com/v3/models/audio/tts")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"language\": \"en\",\n  \"text\": \"Hello from HeyGen Voice.\",\n  \"voice_id\": \"<voice_id>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.heygen.com/v3/models/audio/tts")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"language\": \"en\",\n  \"text\": \"Hello from HeyGen Voice.\",\n  \"voice_id\": \"<voice_id>\"\n}"

response = http.request(request)
puts response.read_body

{
  "data": {
    "audio_url": "<string>",
    "duration": 1,
    "original_characters": [
      {
        "text": "<string>",
        "start_time": 1,
        "end_time": 1
      }
    ]
  }
}

Video Agent

Brand

Avatars

Audio

Voices

Models

Videos

Templates

Video Translate

Lipsync

HyperFrames

User

API Keys

Webhooks

Folders

Assets

AI Clipping

Filler Word Removal

Batches

Video Translation Batches

Lipsync Batches

Asset Batches

Generate Speech

Voice and settings

Language

Limits and request ID

Authorizations

Body

Response