Speech (OpenAI-compatible)

curl --request POST \
  --url https://api.bland.ai/v2/audio/speech \
  --header 'Content-Type: application/json' \
  --header 'authorization: <authorization>' \
  --data '
{
  "model": "<string>",
  "input": "<string>",
  "voice": "<string>",
  "response_format": "<string>",
  "speed": 123,
  "stream_format": "<string>",
  "instructions": "<string>"
}
'

import requests

url = "https://api.bland.ai/v2/audio/speech"

payload = {
    "model": "<string>",
    "input": "<string>",
    "voice": "<string>",
    "response_format": "<string>",
    "speed": 123,
    "stream_format": "<string>",
    "instructions": "<string>"
}
headers = {
    "authorization": "<authorization>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {authorization: '<authorization>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    model: '<string>',
    input: '<string>',
    voice: '<string>',
    response_format: '<string>',
    speed: 123,
    stream_format: '<string>',
    instructions: '<string>'
  })
};

fetch('https://api.bland.ai/v2/audio/speech', 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.bland.ai/v2/audio/speech",
  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([
    'model' => '<string>',
    'input' => '<string>',
    'voice' => '<string>',
    'response_format' => '<string>',
    'speed' => 123,
    'stream_format' => '<string>',
    'instructions' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "authorization: <authorization>"
  ],
]);

$response = curl_exec($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.bland.ai/v2/audio/speech"

	payload := strings.NewReader("{\n  \"model\": \"<string>\",\n  \"input\": \"<string>\",\n  \"voice\": \"<string>\",\n  \"response_format\": \"<string>\",\n  \"speed\": 123,\n  \"stream_format\": \"<string>\",\n  \"instructions\": \"<string>\"\n}")

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

	req.Header.Add("authorization", "<authorization>")
	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.bland.ai/v2/audio/speech")
  .header("authorization", "<authorization>")
  .header("Content-Type", "application/json")
  .body("{\n  \"model\": \"<string>\",\n  \"input\": \"<string>\",\n  \"voice\": \"<string>\",\n  \"response_format\": \"<string>\",\n  \"speed\": 123,\n  \"stream_format\": \"<string>\",\n  \"instructions\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.bland.ai/v2/audio/speech")

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

request = Net::HTTP::Post.new(url)
request["authorization"] = '<authorization>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"model\": \"<string>\",\n  \"input\": \"<string>\",\n  \"voice\": \"<string>\",\n  \"response_format\": \"<string>\",\n  \"speed\": 123,\n  \"stream_format\": \"<string>\",\n  \"instructions\": \"<string>\"\n}"

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

{
  "x-request-id": "<string>"
}

POST

audio

speech

Speech (OpenAI-compatible)

curl --request POST \
  --url https://api.bland.ai/v2/audio/speech \
  --header 'Content-Type: application/json' \
  --header 'authorization: <authorization>' \
  --data '
{
  "model": "<string>",
  "input": "<string>",
  "voice": "<string>",
  "response_format": "<string>",
  "speed": 123,
  "stream_format": "<string>",
  "instructions": "<string>"
}
'

import requests

url = "https://api.bland.ai/v2/audio/speech"

payload = {
    "model": "<string>",
    "input": "<string>",
    "voice": "<string>",
    "response_format": "<string>",
    "speed": 123,
    "stream_format": "<string>",
    "instructions": "<string>"
}
headers = {
    "authorization": "<authorization>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {authorization: '<authorization>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    model: '<string>',
    input: '<string>',
    voice: '<string>',
    response_format: '<string>',
    speed: 123,
    stream_format: '<string>',
    instructions: '<string>'
  })
};

fetch('https://api.bland.ai/v2/audio/speech', 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.bland.ai/v2/audio/speech",
  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([
    'model' => '<string>',
    'input' => '<string>',
    'voice' => '<string>',
    'response_format' => '<string>',
    'speed' => 123,
    'stream_format' => '<string>',
    'instructions' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "authorization: <authorization>"
  ],
]);

$response = curl_exec($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.bland.ai/v2/audio/speech"

	payload := strings.NewReader("{\n  \"model\": \"<string>\",\n  \"input\": \"<string>\",\n  \"voice\": \"<string>\",\n  \"response_format\": \"<string>\",\n  \"speed\": 123,\n  \"stream_format\": \"<string>\",\n  \"instructions\": \"<string>\"\n}")

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

	req.Header.Add("authorization", "<authorization>")
	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.bland.ai/v2/audio/speech")
  .header("authorization", "<authorization>")
  .header("Content-Type", "application/json")
  .body("{\n  \"model\": \"<string>\",\n  \"input\": \"<string>\",\n  \"voice\": \"<string>\",\n  \"response_format\": \"<string>\",\n  \"speed\": 123,\n  \"stream_format\": \"<string>\",\n  \"instructions\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.bland.ai/v2/audio/speech")

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

request = Net::HTTP::Post.new(url)
request["authorization"] = '<authorization>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"model\": \"<string>\",\n  \"input\": \"<string>\",\n  \"voice\": \"<string>\",\n  \"response_format\": \"<string>\",\n  \"speed\": 123,\n  \"stream_format\": \"<string>\",\n  \"instructions\": \"<string>\"\n}"

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

{
  "x-request-id": "<string>"
}

Overview

This endpoint implements OpenAI’s /audio/speech contract. If you already use an OpenAI SDK or a compatible router such as LiteLLM, change the base URL, API key, and model to route speech through Bland.

import os
from pathlib import Path

from openai import OpenAI

client = OpenAI(
    api_key=os.environ["BLAND_API_KEY"],
    base_url="https://api.bland.ai/v2",
)

with client.audio.speech.with_streaming_response.create(
    model="btts-3",
    voice="coral",
    input="Hello from Bland.",
) as response:
    response.stream_to_file(Path("hello.mp3"))

For LLM tokens, interruptions, and the lowest conversational latency, use Realtime Speech (WebSocket). For a complete input string with Bland-specific audio controls, use Synthesize Speech (HTTP).

Headers

string

required

Bearer <your API key>. OpenAI SDKs send this from their api_key or apiKey configuration.

Body parameters

string

required

btts-3 or btts-2.OpenAI model IDs such as tts-1 and gpt-4o-mini-tts are not aliased. Unknown IDs return 400 with code model_not_found.The model must match the selected Bland voice. A mismatch returns 400 with code model_voice_mismatch.

string

required

Non-empty text to speak. Maximum 4,096 characters.

string

required

A recognized OpenAI voice name, mapped to a Bland core voice, or a Bland voice UUID for the full catalog.

OpenAI name	Bland voice
`alloy`, `ash`, `coral`, `fable`	River
`amber`, `august`, `lily`, `nova`, `shimmer`	Karen
`ballad`, `blue`, `echo`, `onyx`, `sage`, `verse`	Matthew

Names are case-insensitive. An unrecognized name returns 400.

string

default:"mp3"

mp3, opus, aac, flac, wav, or pcm.pcm is raw 24 kHz signed 16-bit little-endian mono audio. The other formats use a 48 kHz render and include their normal file or stream framing.

number

default:"1.0"

Only 1.0 is accepted. Other values return 400 because Bland does not currently expose speed control on this endpoint.

string

default:"audio"

Only audio is supported. sse returns 400.

string

Accepted and ignored. This OpenAI field has no Bland equivalent.

Response

The response body contains audio bytes. Content-Type matches the requested format:

`response_format`	`Content-Type`
`mp3`	`audio/mpeg`
`opus`	`audio/ogg`
`aac`	`audio/aac`
`flac`	`audio/flac`
`wav`	`audio/wav`
`pcm`	`audio/pcm`

MP3, Opus, AAC, FLAC, and raw PCM can begin streaming before synthesis completes. WAV is buffered until its final RIFF header length is known.

string

Unique request ID. Include it in support requests.

Errors

Errors use OpenAI’s envelope so SDK error handling remains readable:

{
  "error": {
    "message": "The model 'tts-1' does not exist. Supported models: btts-3, btts-2.",
    "type": "invalid_request_error",
    "param": "model",
    "code": "model_not_found"
  }
}

Condition	HTTP	Code
Missing or malformed field	400	`null`
Unknown model	400	`model_not_found`
Model does not match the selected voice	400	`model_voice_mismatch`
Unsupported voice type	400	`null`
Out of credits	402	`insufficient_quota`
Professional voice is still a draft	403	`voice_not_live`
Voice UUID is not found or accessible	404	`voice_not_found`
Synthesis fails before audio begins	500	`synthesis_failed`

Examples

curl -X POST "https://api.bland.ai/v2/audio/speech" \
  -H "Authorization: Bearer $BLAND_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "btts-3",
    "input": "Hello from Bland.",
    "voice": "coral",
    "response_format": "mp3"
  }' \
  --output hello.mp3

import os
from pathlib import Path

from openai import OpenAI

client = OpenAI(
    api_key=os.environ["BLAND_API_KEY"],
    base_url="https://api.bland.ai/v2",
)

with client.audio.speech.with_streaming_response.create(
    model="btts-3",
    voice="coral",
    input="Hello from Bland.",
) as response:
    response.stream_to_file(Path("hello.mp3"))

import os

import litellm

litellm.speech(
    model="openai/btts-3",
    voice="coral",
    input="Hello from Bland.",
    api_base="https://api.bland.ai/v2",
    api_key=os.environ["BLAND_API_KEY"],
)

import fs from "node:fs/promises";
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.BLAND_API_KEY,
  baseURL: "https://api.bland.ai/v2",
});

const response = await client.audio.speech.create({
  model: "btts-3",
  voice: "coral",
  input: "Hello from Bland.",
});

await fs.writeFile("hello.mp3", Buffer.from(await response.arrayBuffer()));

Docs for agents: llms.txt

⌘I

Get Started

Realtime Speech

HTTP Speech

Migrate

Voice Cloning

Voices

Discovery

Samples

Generation History

Models

Tooling

Speech (OpenAI-compatible)

Overview

Headers

Body parameters

Response

Errors

Examples

​Overview

​Headers

​Body parameters

​Response

​Errors

​Examples

Overview

Headers

Body parameters

Response

Errors

Examples