supertonic
supertone-inc
Fast on-device TTS via ONNX with 31-language support, running on CPU, browser and mobile.
What is supertonic?
A very fast on-device TTS that runs natively through ONNX, with a compact ~99M-parameter model. It covers 31 languages, runs on CPU without a GPU, and even does browser inference via WebGPU.
Pros & Cons
Pros
- Runs on CPU - Raspberry Pi, mobile, browser, no network needed
- Real-time (a whole web page narrated in under a second)
- SDKs across Python, Node, browser, Java, C++, Swift, iOS, Rust, Flutter
Cons
- No built-in voice cloning in the open variant (fixed voice only)
- The model is OpenRAIL-M, so this is open-weight with use restrictions, not fully OSI-open
- 78 open issues at time of writing
License
MIT (code) (Open weight, with conditions) - model license: OpenRAIL-M
Code MIT, model OpenRAIL-M (open weight, with conditions).
When it is interesting
Edge, on-device or browser TTS where latency and privacy matter.
When it is too early
If you need out-of-the-box cloning or want to avoid the OpenRAIL-M use clauses commercially.
Commercial alternative & related
- Commercial counterpart: Supertone Play/API
This repo featured in the 2026-06 edition of the Open-Source AI Radar.
voicebox
jamiepine
A free, on-device alternative to ElevenLabs for TTS, voice cloning and dictation.
VoxCPM
OpenBMB
Tokenizer-free TTS from OpenBMB covering 30 languages with voice design and real-time streaming.
Chatterbox
resemble-ai
MIT-licensed open TTS with zero-shot voice cloning - 500M params, 23+ languages.