Is this Portuguese text-to-speech really free?

Yes. The page is public, no signup is required, and there are no credit limits. The voice model runs entirely in your browser. For studio-grade voices and longer narration, see the paid Subformer Voice Synthesis service.

How does the Portuguese TTS work in the browser?

It uses Piper, an open-source neural TTS engine, compiled to WebAssembly and run via ONNX Runtime Web. The voice model (~60 MB) is downloaded on first use and cached in your browser's Origin Private File System. Subsequent visits skip the download entirely.

Is my text uploaded to a server?

No. Synthesis runs locally in your browser. The only network calls are to download the Piper voice model and the ONNX runtime — both are static assets. Your text and the generated audio never leave your device.

Does it work offline?

Once the voice model is cached, yes. The first visit needs network access to download the model; after that the page can synthesize speech offline.

What's the difference between this free Portuguese TTS and the paid Voice Synthesis service?

The free in-browser TTS uses a medium-quality Piper voice — fine for narration drafts, accessibility, and quick previews, but it sounds noticeably synthetic. The paid Subformer Voice Synthesis service uses studio-grade models (Chatterbox + Gemini TTS), supports voice cloning, and produces broadcast-quality audio. Visit /dashboard/voice-synthesis to try it.

Which browsers are supported?

Any modern browser with WebAssembly: Chrome, Firefox, Safari 15+, Edge, and Chromium-based mobile browsers. The page runs ORT in single-threaded mode so it works in every common browser without requiring cross-origin isolation.

Can I download the audio?

Yes. After synthesis you can play the audio inline or click Download to save it as a 22 kHz mono WAV file. Use any audio editor to convert to MP3 or other formats.