What Is Text to Speech? Free Open-Source TTS Engines Explained

About

What is text to speech?

Text to speech (TTS) is technology that converts written words into spoken audio using a synthetic voice — and Text-to-voice.app makes it free, private and instant in your browser.

What Text to Speech Means

Text to speech, also called speech synthesis, is the automated process of turning text into a human-like voice. You provide a string of words; a speech engine analyzes the language, works out how each word should sound, and produces an audio waveform you can play or save. It's the same family of technology behind screen readers, voice assistants, GPS navigation and audiobook narration.

Unlike a recording of a real person, synthetic speech can read any text on demand, in many languages, at any length — which is exactly what makes a free TTS generator so useful for creators, educators and developers. See it in action on the text to voice converter, or follow our step-by-step tutorials.

How speech synthesis works

01

Text analysis

The engine normalizes your text — expanding numbers, dates and abbreviations into full words and splitting it into sentences.

02

Phonetic conversion

Words are mapped to phonemes — the individual sounds of speech — along with stress, intonation and timing for each language.

03

Audio generation

A synthesizer turns those phonemes into a sound wave — which you hear instantly and can download as a file.

Types of TTS

Formant

Generates sound from acoustic rules. Tiny, fast and works fully offline in any language — used by classic engines like eSpeak NG.

Concatenative

Stitches together recorded snippets of a real human voice for a more natural result, at the cost of larger voice data.

Neural

Uses deep-learning models to produce highly natural, expressive voices. Piper — the engine powering this site — and projects like Coqui use this approach.

Open source

Free & open-source text to speech engines

The open-source community has built dozens of powerful, free text to speech engines. Browse the projects below, explore their code on GitHub, and pick whichever fits your needs.

Piper

Neural · VITS

Fast, high-quality neural speech designed to run locally on-device.

github.com/rhasspy/piper

Coqui TTS

Deep-learning toolkit

A rich toolkit for training and running expressive neural voices, including XTTS.

github.com/coqui-ai/TTS

eSpeak NG

Compact formant

A tiny synthesizer supporting 100+ languages, ideal for low-resource devices.

github.com/espeak-ng/espeak-ng

Tortoise TTS

Expressive neural

Produces extremely realistic, expressive voices with strong voice cloning.

github.com/neonbjb/tortoise-tts

StyleTTS 2

Human-level neural

Style-diffusion model delivering natural prosody and human-level quality.

github.com/yl4579/StyleTTS2

Bark

Generative audio

A transformer model that generates multilingual speech, music and sound effects.

github.com/suno-ai/bark

MaryTTS

Modular · Java

A long-standing, modular multilingual synthesis platform built in Java.

github.com/marytts/marytts

Festival

Concatenative

The classic research engine from the University of Edinburgh's CSTR.

github.com/festvox/festival

RHVoice

Accessibility

A multilingual engine widely used by screen readers and assistive tech.

github.com/RHVoice/RHVoice

VITS

End-to-end neural

The end-to-end architecture behind many modern neural voices.

github.com/jaywalnut310/vits

Tacotron 2

Seq2seq neural

NVIDIA's influential sequence-to-sequence model with a WaveNet vocoder.

github.com/NVIDIA/tacotron2

OpenTTS

Unified API

A single HTTP API that wraps many open-source engines and their voices.

github.com/synesthesiam/opentts

Free, open, and private by design

Because the speech engines run inside your browser, your text never leaves your device — and the tool stays completely free. No accounts, no quotas, no tracking.

Generate Unlimited AI Voiceover