The best local TTS engine depends on your hardware, language and goal. This guide compares four engines you can run free in a browser.
How local TTS works
Local engines use WebAssembly for speed and WebGPU for the graphics card. Model files download once. Later runs are fast and can work offline.
Kokoro
Kokoro has 82 million parameters. It is the most human-like option. It supports 8 languages and 54 voices, including Spanish and French. The model is about 326 MB. WebGPU is recommended, with a WASM fallback.
Piper
Piper runs on CPU. It covers hundreds of voices in many languages, including Polish. Models weigh 20 to 109 MB. It is the best default for old hardware and everyday work.
Kitten and eSpeak
Kitten is a tiny test model under 25 MB. It has English voices only. It fits weak devices.
eSpeak NG needs no download. It supports over 100 languages and starts at once. The voice is robotic but great for screen readers.
Comparison
| Feature | Kokoro | Piper | Kitten | eSpeak NG |
|---|---|---|---|---|
| Voice quality | Ultra-realistic | Natural | Light | Robotic |
| Model size | ~326 MB | ~20-109 MB | under 25 MB | No download |
| Hardware | WebGPU recommended | Any CPU | Any CPU | Minimal |
| Languages | 8 | Hundreds of voices | English only | 100+ languages |
Which one to pick
- Want realism in a supported language? Choose Kokoro.
- Need Polish, more accents or old hardware? Choose Piper.
- Have a very weak phone? Try Kitten, English only.
- Need instant, tiny, multilingual output? Use eSpeak NG.
Test all four in the same browser generator. For a two-engine duel, read Kokoro vs Piper.
Frequently Asked Questions (FAQ)
What is the best free local TTS engine?
Piper is the best all-round default for speed, low hardware needs and language coverage. Kokoro wins on realism if you have WebGPU.
Are local TTS engines really unlimited?
Yes. Synthesis happens on your device. There is no character limit and no per-use fee.
Which engine supports the most languages?
eSpeak NG supports over 100 languages. Piper offers hundreds of voices across many of them.
Does Kitten TTS work in other languages?
No. Kitten TTS provides English voices only.