Free Text-to-Speech API - 300+ Voices in 70+ Languages

Convert text to natural speech with our TTS API. 300+ voices, 70+ languages, multiple audio formats. Free tier with generous limits.

Converting text to natural-sounding speech is one of the most in-demand features in modern applications. From accessibility tools and e-learning platforms to voice assistants and content creation workflows, text-to-speech (TTS) technology has become essential. This guide covers everything you need to know about the DevProToolkit Text-to-Speech API — a free, developer-friendly service that offers over 300 neural voices across 70+ languages.

Powered by the edge-tts engine, this API delivers remarkably human-like speech synthesis without the complexity or cost of building your own TTS pipeline. Whether you need a single audio clip or want to integrate speech synthesis into a production application serving thousands of users, this API has you covered.

What Is a Text-to-Speech API?

A text-to-speech API is a web service that accepts text input and returns an audio file containing a spoken rendition of that text. Modern TTS APIs use neural network models to produce speech that closely resembles a natural human voice, with proper intonation, pacing, and emphasis.

The DevProToolkit TTS API accepts a POST request with your text and preferred voice, and returns an MP3 audio file ready for playback, download, or further processing. It supports:

• 300+ neural voices across male, female, and neutral options
• 70+ languages and regional accents including English (US, UK, AU, IN), Spanish, French, German, Japanese, Chinese, Arabic, Hindi, and many more
• SSML markup for fine-grained control over pronunciation, pauses, emphasis, and prosody
• Adjustable speech rate and pitch to match your application's needs
• MP3 output that works everywhere — browsers, mobile apps, and desktop applications

Why Use This TTS API?

There are several TTS APIs on the market — Google Cloud TTS, Amazon Polly, Azure Cognitive Services, and ElevenLabs among them. Here is why the DevProToolkit TTS API is worth considering:

• Genuinely free tier: 100 requests per day with no credit card required. Most alternatives require a credit card at signup or charge per character.
• No character limits per request: Many competitors cap individual requests at 500 or 1,000 characters. Our API handles long-form text efficiently.
• Simple REST interface: A single POST endpoint handles everything. No SDKs, client libraries, or OAuth flows required.
• Neural-quality voices: Powered by the edge-tts engine, the same technology behind Microsoft's neural voice offerings.
• No data retention: Your text is processed and discarded. We do not store, log, or train on your content.
• Voice discovery endpoints: Programmatically list all available voices and languages so you can build dynamic voice selectors in your UI.

Getting Started in Under a Minute

Three steps to your first synthesized audio:

1. Get a free API key at /signup
2. POST your text to the speak endpoint
3. Save the MP3 response

curl -X POST "https://api.commandsector.in/api/tts/speak" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "Hello! Welcome to the DevProToolkit text-to-speech API.", "voice": "en-US-ChristopherNeural"}' \
  -o welcome.mp3

Play the resulting welcome.mp3 file and you will hear a natural male American English voice reading your text. The entire process takes under a second for short texts.

API Reference & Endpoints

1. Synthesize Speech

POST /api/tts/speak

Request body (JSON):

Field	Type	Required	Description
text	string	Yes	The text to convert to speech
voice	string	No	Voice identifier (default: en-US-ChristopherNeural)
rate	string	No	Speech rate adjustment, e.g., +20% or -10% (default: +0%)
pitch	string	No	Pitch adjustment, e.g., +5Hz or -10Hz (default: +0Hz)

Response: audio/mpeg binary data (MP3 file)

2. List Voices for a Language

GET /api/tts/voices/{language_code}

Returns a JSON array of all available voices for the specified language. For example, /api/tts/voices/en returns all English voices across all regional variants.

curl "https://api.commandsector.in/api/tts/voices/en" \
  -H "X-API-Key: YOUR_API_KEY"

Example response:

[
  {
    "name": "en-US-ChristopherNeural",
    "gender": "Male",
    "locale": "en-US",
    "language": "English (United States)"
  },
  {
    "name": "en-US-JennyNeural",
    "gender": "Female",
    "locale": "en-US",
    "language": "English (United States)"
  },
  {
    "name": "en-GB-RyanNeural",
    "gender": "Male",
    "locale": "en-GB",
    "language": "English (United Kingdom)"
  }
]

3. List All Supported Languages

GET /api/tts/languages

Returns a JSON array of all supported language codes and their display names.

curl "https://api.commandsector.in/api/tts/languages" \
  -H "X-API-Key: YOUR_API_KEY"

Popular Voices & How to Choose

With over 300 voices available, picking the right one matters. Here are the most popular voices organized by language and use case:

English Voices

Voice ID	Gender	Accent	Best For
en-US-ChristopherNeural	Male	American	Narration, tutorials, professional content
en-US-JennyNeural	Female	American	Customer service, e-learning, assistants
en-US-GuyNeural	Male	American	Casual content, podcasts, blogs
en-US-AriaNeural	Female	American	General purpose, news reading
en-GB-RyanNeural	Male	British	Formal content, documentaries
en-GB-SoniaNeural	Female	British	Audiobooks, storytelling
en-AU-WilliamNeural	Male	Australian	Regional content, travel apps
en-IN-NeerjaNeural	Female	Indian	India-market applications

Other Popular Language Voices

Voice ID	Language	Gender
es-ES-AlvaroNeural	Spanish (Spain)	Male
es-MX-DaliaNeural	Spanish (Mexico)	Female
fr-FR-HenriNeural	French	Male
de-DE-ConradNeural	German	Male
ja-JP-KeitaNeural	Japanese	Male
zh-CN-XiaoxiaoNeural	Chinese (Mandarin)	Female
hi-IN-MadhurNeural	Hindi	Male
ar-SA-HamedNeural	Arabic (Saudi)	Male
pt-BR-AntonioNeural	Portuguese (Brazil)	Male
ko-KR-InJoonNeural	Korean	Male

Tip: Use the /api/tts/voices/{lang} endpoint to programmatically discover all voices for a language. This lets you build voice selector dropdowns in your UI that automatically stay up to date as new voices are added.

Supported Languages (70+)

The API supports over 70 languages and regional variants. Here is a partial list of the most commonly used ones:

Language	Code	Voices Available
English (US, UK, AU, IN, CA)	en	20+
Spanish (ES, MX, AR, CO)	es	15+
French (FR, CA)	fr	10+
German	de	8+
Chinese (Mandarin, Cantonese)	zh	15+
Japanese	ja	6+
Korean	ko	4+
Hindi	hi	4+
Arabic	ar	8+
Portuguese (BR, PT)	pt	8+
Italian	it	4+
Dutch	nl	4+
Russian	ru	4+
Turkish	tr	4+
Polish	pl	4+
Swedish	sv	2+
Thai	th	2+
Vietnamese	vi	2+

For the complete list, call the /api/tts/languages endpoint or visit the TTS Playground to browse all options interactively.

cURL Examples

Basic Speech Synthesis

curl -X POST "https://api.commandsector.in/api/tts/speak" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "The quick brown fox jumps over the lazy dog.", "voice": "en-US-ChristopherNeural"}' \
  -o speech.mp3

Female British Voice

curl -X POST "https://api.commandsector.in/api/tts/speak" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "Good afternoon. This is an example of British English speech synthesis.", "voice": "en-GB-SoniaNeural"}' \
  -o british.mp3

Spanish with Adjusted Speed

curl -X POST "https://api.commandsector.in/api/tts/speak" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "Hola, bienvenido a nuestra plataforma de servicios.", "voice": "es-ES-AlvaroNeural", "rate": "-15%"}' \
  -o spanish_slow.mp3

Japanese Narration

curl -X POST "https://api.commandsector.in/api/tts/speak" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "こんにちは、開発者ツールキットへようこそ。", "voice": "ja-JP-KeitaNeural"}' \
  -o japanese.mp3

List All English Voices

curl "https://api.commandsector.in/api/tts/voices/en" \
  -H "X-API-Key: YOUR_API_KEY" | python3 -m json.tool

Python Integration

Basic Text-to-Speech

import requests

API_KEY = "YOUR_API_KEY"
BASE_URL = "https://api.commandsector.in"

def text_to_speech(text, voice="en-US-ChristopherNeural", rate="+0%", output_file="output.mp3"):
    """Convert text to speech and save as MP3."""
    response = requests.post(
        f"{BASE_URL}/api/tts/speak",
        json={
            "text": text,
            "voice": voice,
            "rate": rate
        },
        headers={"X-API-Key": API_KEY}
    )

    if response.status_code == 200:
        with open(output_file, "wb") as f:
            f.write(response.content)
        print(f"Audio saved to {output_file}")
        return output_file
    else:
        print(f"Error: {response.status_code} - {response.text}")
        return None

# Generate speech
text_to_speech(
    "Welcome to our platform. This tutorial will guide you through the setup process.",
    voice="en-US-JennyNeural",
    output_file="welcome_tutorial.mp3"
)

Build a Voice Selection UI with Available Voices

import requests

API_KEY = "YOUR_API_KEY"
BASE_URL = "https://api.commandsector.in"

def get_voices(language="en"):
    """Retrieve all available voices for a language."""
    response = requests.get(
        f"{BASE_URL}/api/tts/voices/{language}",
        headers={"X-API-Key": API_KEY}
    )
    return response.json()

def get_languages():
    """Retrieve all supported languages."""
    response = requests.get(
        f"{BASE_URL}/api/tts/languages",
        headers={"X-API-Key": API_KEY}
    )
    return response.json()

# List all English voices
voices = get_voices("en")
print(f"Found {len(voices)} English voices:\n")
for voice in voices:
    print(f"  {voice['name']:40s} {voice['gender']:8s} {voice['locale']}")

# List all supported languages
languages = get_languages()
print(f"\nSupported languages: {len(languages)}")
for lang in languages[:10]:
    print(f"  {lang}")

Audio Blog Post Generator

import requests
import os

API_KEY = "YOUR_API_KEY"
BASE_URL = "https://api.commandsector.in"

def generate_audio_article(paragraphs, voice="en-US-ChristopherNeural", output_dir="audio"):
    """Convert a list of paragraphs into individual audio files."""
    os.makedirs(output_dir, exist_ok=True)

    for i, paragraph in enumerate(paragraphs):
        if not paragraph.strip():
            continue

        response = requests.post(
            f"{BASE_URL}/api/tts/speak",
            json={"text": paragraph.strip(), "voice": voice},
            headers={"X-API-Key": API_KEY}
        )

        if response.status_code == 200:
            filepath = os.path.join(output_dir, f"section_{i+1:03d}.mp3")
            with open(filepath, "wb") as f:
                f.write(response.content)
            print(f"Generated: {filepath}")
        else:
            print(f"Failed on paragraph {i+1}: {response.status_code}")

# Example usage
blog_post = [
    "Welcome to today's article about building scalable web applications.",
    "In the first section, we will discuss the importance of API design.",
    "Next, we will cover database optimization techniques.",
    "Finally, we will look at deployment strategies for high-traffic sites."
]

generate_audio_article(blog_post, voice="en-US-GuyNeural")

Node.js Integration

Basic Text-to-Speech

const fs = require('fs');

const API_KEY = 'YOUR_API_KEY';
const BASE_URL = 'https://api.commandsector.in';

async function textToSpeech(text, voice = 'en-US-ChristopherNeural', outputFile = 'output.mp3') {
  const response = await fetch(`${BASE_URL}/api/tts/speak`, {
    method: 'POST',
    headers: {
      'X-API-Key': API_KEY,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ text, voice }),
  });

  if (!response.ok) {
    throw new Error(`TTS API error: ${response.status}`);
  }

  const buffer = Buffer.from(await response.arrayBuffer());
  fs.writeFileSync(outputFile, buffer);
  console.log(`Audio saved to ${outputFile}`);
}

// Generate speech
textToSpeech(
  'This is a test of the text-to-speech API from Node.js.',
  'en-US-JennyNeural',
  'test_speech.mp3'
);

Express.js API Proxy for Browser Playback

const express = require('express');
const app = express();
app.use(express.json());

const API_KEY = 'YOUR_API_KEY';
const BASE_URL = 'https://api.commandsector.in';

// Endpoint for your frontend to request speech synthesis
app.post('/api/speak', async (req, res) => {
  const { text, voice = 'en-US-JennyNeural' } = req.body;

  if (!text || text.length > 5000) {
    return res.status(400).json({ error: 'Text is required and must be under 5000 characters' });
  }

  try {
    const ttsResponse = await fetch(`${BASE_URL}/api/tts/speak`, {
      method: 'POST',
      headers: {
        'X-API-Key': API_KEY,
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({ text, voice }),
    });

    if (!ttsResponse.ok) {
      return res.status(502).json({ error: 'TTS service error' });
    }

    // Stream the audio response to the client
    res.set('Content-Type', 'audio/mpeg');
    const buffer = Buffer.from(await ttsResponse.arrayBuffer());
    res.send(buffer);
  } catch (err) {
    res.status(500).json({ error: 'Internal server error' });
  }
});

// Endpoint to get available voices
app.get('/api/voices/:lang', async (req, res) => {
  const response = await fetch(`${BASE_URL}/api/tts/voices/${req.params.lang}`, {
    headers: { 'X-API-Key': API_KEY },
  });
  const voices = await response.json();
  res.json(voices);
});

app.listen(3000, () => console.log('Server running on port 3000'));

Browser-Side Playback

// Frontend code to play TTS audio in the browser
async function speakText(text, voice = 'en-US-JennyNeural') {
  const response = await fetch('/api/speak', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ text, voice }),
  });

  if (!response.ok) throw new Error('Speech synthesis failed');

  const audioBlob = await response.blob();
  const audioUrl = URL.createObjectURL(audioBlob);
  const audio = new Audio(audioUrl);
  audio.play();

  // Clean up when done
  audio.addEventListener('ended', () => URL.revokeObjectURL(audioUrl));
}

// Usage
document.getElementById('speak-btn').addEventListener('click', () => {
  const text = document.getElementById('text-input').value;
  speakText(text);
});

SSML Support & Advanced Controls

Speech Synthesis Markup Language (SSML) gives you fine-grained control over how the text is spoken. You can add pauses, change emphasis, spell out words, and more. Pass SSML as the text field in your request.

Adding Pauses

<speak>
  Welcome to our service.
  <break time="500ms"/>
  Let me walk you through the features.
  <break time="1s"/>
  First, let us look at the dashboard.
</speak>

Emphasis and Prosody

<speak>
  This is <emphasis level="strong">extremely important</emphasis> information.
  <prosody rate="slow" pitch="+2st">Please read this carefully.</prosody>
</speak>

Spelling Out Characters

<speak>
  Your confirmation code is
  <say-as interpret-as="characters">ABCD1234</say-as>.
</speak>

Full SSML Example with cURL

curl -X POST "https://api.commandsector.in/api/tts/speak" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "Welcome!  Your order XK42 has been confirmed. Thank you for your purchase.",
    "voice": "en-US-JennyNeural"
  }' \
  -o ssml_demo.mp3

Speech Rate & Pitch Adjustment

The rate and pitch parameters let you adjust how fast and how high or low the voice sounds:

Parameter	Format	Range	Example
rate	Percentage	-50% to +100%	+20% (20% faster)
pitch	Hertz offset	-50Hz to +50Hz	-10Hz (slightly lower)

Common Rate Settings

• -30% — Slow, deliberate speech for accessibility or language learners
• -15% — Slightly slower for narration and tutorials
• +0% — Natural default speed
• +15% — Slightly faster for summaries or news reading
• +30% — Fast narration for experienced listeners

# Python: Generate the same text at different speeds
import requests

API_KEY = "YOUR_API_KEY"
BASE_URL = "https://api.commandsector.in"
text = "Understanding speech rate control helps you tailor the listening experience."

for rate in ["-30%", "+0%", "+30%"]:
    resp = requests.post(f"{BASE_URL}/api/tts/speak", json={
        "text": text,
        "voice": "en-US-ChristopherNeural",
        "rate": rate
    }, headers={"X-API-Key": API_KEY})

    filename = f"rate_{rate.replace('+', 'plus').replace('-', 'minus')}.mp3"
    with open(filename, "wb") as f:
        f.write(resp.content)
    print(f"Generated {filename} at rate {rate}")

Real-World Use Cases

Accessibility & Screen Readers

Add audio alternatives to your web content for visually impaired users. Generate audio versions of articles, documentation, or notifications and serve them alongside the text.

E-Learning Platforms

Automatically narrate course content, quizzes, and instructions. Use different voices for different characters in educational scenarios. Adjust speech rate for different learning levels.

Podcast & Content Automation

Convert blog posts, newsletters, or research summaries into podcast-style audio. Generate daily briefings or news digests for audio consumption.

IVR & Phone Systems

Generate dynamic voice prompts for interactive voice response systems. Update menu options, announcements, and on-hold messages programmatically without recording studio time.

Language Learning Apps

Present vocabulary and phrases in native-speaker quality across 70+ languages. Use the rate control to offer slow and normal-speed versions of the same content.

Voice Notifications

Generate audio alerts and notifications for IoT devices, smart home systems, or workplace announcement systems. Synthesize real-time alerts from monitoring systems.

Audiobook Creation

Convert manuscripts, short stories, or documentation into audio format. Use SSML for dramatic pauses, emphasis, and character differentiation.

Pricing & Rate Limits

Plan	Requests / Day	Rate Limit	Price
Free	100	10 / minute	$0 / month
Pro	10,000	100 / minute	$9.99 / month
Enterprise	Unlimited	Custom	Contact us

The free tier is perfect for prototyping, personal projects, and low-volume production use. Each request can contain a substantial amount of text, so 100 requests per day goes further than you might expect. Get your free API key here.

Frequently Asked Questions

Is the TTS API really free?

Yes. The free tier provides 100 requests per day with no credit card required. Sign up at /signup and start synthesizing speech immediately. No trial period or expiration date — the free tier is permanent.

What audio format does the API return?

The API returns MP3 audio (audio/mpeg), which is universally supported across all browsers, mobile devices, and desktop media players. MP3 offers an excellent balance of quality and file size.

Is there a character limit per request?

The API supports long-form text input. While there is no strict character limit published, we recommend keeping individual requests under 5,000 characters for optimal performance. For longer content, split it into paragraphs and make multiple requests.

How natural do the voices sound?

The voices are powered by the edge-tts neural engine, which produces remarkably natural speech with proper intonation, rhythm, and emphasis. They are comparable in quality to premium TTS services. Try them in the TTS Playground to hear for yourself.

Can I use the generated audio commercially?

Yes. Audio generated through our API can be used in commercial applications, products, and content. There are no royalty fees or licensing restrictions on the output audio files.

Does the API support SSML?

Yes. You can pass SSML markup in the text field to control pauses, emphasis, pronunciation, speed, and pitch at a granular level. See the SSML section above for detailed examples.

What is the edge-tts engine?

Edge-tts is a high-quality neural text-to-speech engine that powers the speech synthesis. It provides the same voice technology used in Microsoft Edge's read-aloud feature, delivering natural and expressive speech across hundreds of voices and dozens of languages.

Can I list available voices programmatically?

Yes. Use GET /api/tts/voices/{language_code} to get all voices for a specific language, or GET /api/tts/languages to list all supported languages. This allows you to build dynamic voice selectors that automatically include new voices as they are added.

Quick Start - Code Examples

cURL

curl -X POST "https://api.commandsector.in/api/tts/synthesize" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "Hello world", "voice": "en-US-JennyNeural"}' \
  -o speech.mp3

Python

import requests

response = requests.post("https://api.commandsector.in/api/tts/synthesize", json={
    "text": "Hello, this is a test",
    "voice": "en-US-JennyNeural",
    "rate": "+0%"
}, headers={"X-API-Key": "YOUR_API_KEY"})

with open("speech.mp3", "wb") as f:
    f.write(response.content)