Supertonic

Supertonic by Supertone is an on-device text-to-speech engine that runs entirely in your browser or on-device with zero network dependency. It supports 31 languages, real-time synthesis, and a Voice Builder for creating custom voices. It's fast enough to run on a Raspberry Pi or an e-reader, bringing private, offline narration anywhere.

Best for: Anyone who wants fast, private TTS in the browser or on low-power devices

• ✓ Runs on-device and in-browser — zero network dependency
• ✓ 31 languages
• ✓ Custom voice creation with Voice Builder
• ✓ Real-time synthesis (0.3x RTF on e-readers)
• ✓ Output styles: announcement, chatbot, podcast, article
• ✓ Works on desktop, iOS, and Raspberry Pi