# Text to Speech > Free text to speech in your browser with no character limit. Long texts are synthesized in parts of 10,000 characters. Listen, then download a WAV. - URL: https://bytescope.dev/en/text-to-speech/ - Locale: en · Also: [ja](https://bytescope.dev/ja/text-to-speech.md) · [zh-Hant](https://bytescope.dev/zh-Hant/text-to-speech.md) - Runs: Your text stays in this tab. It is never uploaded, saved or sent with analytics. - Requires: Built-in voices: any browser with the Web Speech synthesis API (voices depend on the operating system). Downloadable voices (Kokoro for Chinese, Supertonic 3 for English and Japanese): any modern desktop browser, much faster with WebGPU; without it they run on the CPU slower than real time. Phones may run out of memory (the models need about 2.5–3 GB while running). - Updated: 2026-09-08 ## What it does Most text to speech sites stop you at a few hundred characters, ask for an account, or send your text to a server to be read out. This page does none of that. The speech is generated inside the browser tab: there is no character limit and no upload — a long article, a whole chapter or a script you have not published yet never leaves your computer. Long texts are synthesized in parts of 10,000 characters. You listen in the page first, and the downloadable engines write a 16-bit mono WAV file when you ask for one. Once a voice model has been downloaded, the page keeps working without a network connection, which makes it an offline text to speech tool as much as a TTS in the browser. ### Three engines, chosen by language The built-in engine uses the Web Speech API (`speechSynthesis`), so the voices are whatever your operating system ships — they differ between Windows, macOS, Android and iOS — and there is nothing to download. Kokoro 82M handles Chinese with 100 voices; it is released under Apache-2.0 and needs a one-time download of about 340 MB for the model plus a 3–4 MB Chinese pronunciation dictionary. Supertonic 3 handles English and Japanese with 10 voices, downloads about 400 MB the first time, and is released under the OpenRAIL-M licence. Supertonic 3 does not speak Chinese, so for Chinese text the choice is between Kokoro and the built-in voice. ### Listen first, download when you are happy Every engine plays in the page before anything is written to disk. While it reads, the sentence being spoken is highlighted, and you can click any sentence to start from there; the speed slider runs from 0.5× to 2.0×. When the result sounds right, the Download WAV button renders the whole text to a file. The built-in engine has no download button, and the FAQ below explains why — the audio goes straight from the browser to your speakers and the page never receives it. ### What to expect from the Chinese voices Kokoro's Chinese voices have a Beijing accent, misread some characters that have more than one pronunciation, and give English words inside a Chinese sentence a noticeable accent. Traditional characters are converted to simplified internally only to look up pronunciations; the text you see is not changed. The built-in voice reads Chinese with whatever voice your operating system provides, so its accent depends on your system — at the cost of not being downloadable. ### Speed and memory With WebGPU available, synthesis is many times faster than real time. Without a usable GPU the models run on the CPU, and long texts then take longer than their playing time — in testing, about 1.5 to 3 times the audio length — so a ten-minute reading is a wait, not a click. While a downloaded model is synthesising, the browser uses roughly 2.5–3 GB of memory, which many phones cannot spare; on a phone the built-in voice is the practical choice. ### What this page does not do There is no voice cloning, no emotion or style control, and no MP3 export — the output is WAV. Model weights are fetched from pinned versions on Hugging Face only after you agree to the download, and the Chinese dictionary is served by this site. Opening the page triggers no download and asks for no permission. Audio quality is what these open models produce; judge it by listening to a sentence of your own text before downloading anything. ## Limits Does not upload your text, does not clone voices, does not control emotion or tone, and does not export MP3. The built-in browser voices can only be played, not downloaded; whether the operating system synthesises them on-device or in the cloud is up to the system and cannot be seen by the page. ## FAQ ### Why can't I download audio from the built-in voice? Because the Web Speech API only plays. `speechSynthesis` hands the text to the operating system, which sends the sound directly to your speakers; the web page never receives the audio data, so there is nothing for it to save. To get a WAV file, use Kokoro (Chinese) or Supertonic 3 (English, Japanese), which synthesise inside the page and can write the result to a file. ### Why does the Chinese voice sound like Beijing Mandarin? Kokoro 82M's 100 Chinese voices all speak Mandarin with a Beijing accent. It also misreads some characters that have more than one pronunciation, and English words inside a Chinese sentence come out with an accent. Traditional text is converted to simplified characters internally to look up pronunciations — what you typed is not altered. The built-in engine uses your operating system's Chinese voice instead, so its accent depends on your system, but that voice cannot be downloaded. ### Is my text uploaded? Not by this page. Kokoro and Supertonic 3 run entirely in the browser, so the text never leaves your device. The built-in engine passes the text to your operating system's speech service; on some systems that service may synthesise in the cloud, and the browser and the OS decide that, not this page — we cannot see or control it. For text you want to be certain stays local, use one of the downloaded engines. ### Can I use the audio commercially? That depends on the licence of the model that produced it, not on this page. Kokoro 82M is released under Apache-2.0. Supertonic 3 is released under OpenRAIL-M, which carries use restrictions — for example, not impersonating others, not using the output to harm people, and labelling published audio as machine-generated; the page lists the terms before the download. The built-in voices are governed by your operating system's terms. Read the relevant licence yourself before publishing or selling anything; this page does not give legal advice. ### Does it work without an internet connection? Yes, once a voice has been downloaded. Kokoro and Supertonic 3 are stored by the browser after the first download, and synthesis runs locally, so the page keeps working offline. The built-in engine depends on your operating system: some system voices are fully local, others may need a network connection, and the page has no way to tell which. ### Why is the first download so large? Because you are downloading the voice model itself, not a list of voices. Kokoro 82M is about 340 MB plus a 3–4 MB Chinese pronunciation dictionary; Supertonic 3 is about 400 MB. That is the price of synthesising in the browser instead of on a server: the model has to be on your machine. The download starts only after you agree, the weights come from pinned versions on Hugging Face, and the browser keeps them so you download once. ### Why is a long text slow? Speed depends on your hardware. With WebGPU, synthesis is much faster than real time. Without a usable GPU the model runs on the CPU, and in testing a long text took about 1.5 to 3 times its audio length to render, so a half-hour reading needs patience. Synthesis also uses roughly 2.5–3 GB of browser memory, which is why phones may fail or run out; the built-in voice has no such cost. ## Related tools - [Voice Notes](https://bytescope.dev/en/voice-notes.md) — The other direction: record your voice with a live transcript → - [Subtitle Converter](https://bytescope.dev/en/subtitle-converter.md) — Convert subtitles between SRT, VTT, ASS and SBV → - [Live Captions](https://bytescope.dev/en/live-captions.md) — Live captions of what you say, with translation → - [Speaker Test](https://bytescope.dev/en/speaker-test.md) — Check left and right channels and bass before you listen →