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license: mit
language: en
library_name: onnx
tags:
- text-to-speech
- tts
- kokoro
- piper
- kittentts
- vits
- styletts2
- onnx
- sherpa-onnx
- on-device
- threadcast
pipeline_tag: text-to-speech
---
<p align="center">
<a href="https://threadcast.app">
<img src="assets/logo.png" alt="ThreadCast" width="160" height="160" />
</a>
</p>
<h1 align="center">ThreadCast — Neural Models Mirror</h1>
<p align="center">
<em>Threads, now a podcast.</em><br/>
<a href="https://threadcast.app">threadcast.app</a> · <a href="https://pixellabs.ventures">pixellabs.ventures</a>
</p>
---
Self-hosted mirror of the on-device neural TTS models used by **[ThreadCast](https://threadcast.app)** across both shipping platforms — the Chrome extension and the Android app. Three engine families on Android (Piper VITS, KittenTTS-nano VITS, Kokoro StyleTTS2), two on the extension, one source of truth.
This repository exists so each platform can ship a stable, version-pinned set of model weights without depending on the availability or rate-limits of upstream Hugging Face repos at runtime.
> **Note:** if you're a ThreadCast user, you don't need anything here — the extension and the Android app each download (or bundle) what they need automatically. This page is for transparency, contributors, and forks.
---
## Repository layout
```
threadcast-neural-models/
├── extension/ ← Chrome extension — HF transformers.js packaging
│ ├── neural-28m/ Piper VITS — 5 voices, raw HF format
│ └── neural-82m/ Kokoro StyleTTS2 — 1 model + 11 voice embeddings
│
└── mobile-android/ ← Android app — production zips fetched at runtime
└── v1/ 8 zips: 1 shared espeak + 5 per-voice Piper
+ 1 KittenTTS-nano ("Local AI Plus")
+ 1 Kokoro ("Local AI Studio")
```
| Subtree | Format | Consumed by | Sub-README |
|---|---|---|---|
| `extension/` | Raw HF (per-file `.onnx`, `.bin`, `tokenizer.json`) | Chrome extension via `@huggingface/transformers` + `@realtimex/piper-tts-web` | [extension/README.md](extension/README.md) |
| `mobile-android/` | ZIP archives, sherpa-onnx packaging | Android app at runtime via [AssetInstaller.kt](https://github.com/Pixel-Labs/Reddit-Reader/blob/main/packages/mobile/modules/threadcast-neural/android/src/main/java/app/threadcast/neural/AssetInstaller.kt) — first-launch download with cancel/delete | [mobile-android/README.md](mobile-android/README.md) |
The two subtrees parallel each other on purpose — same engine families (Piper VITS, Kokoro StyleTTS2), same `neural-28m` / `neural-82m` parameter-count naming, just packaged for each platform's runtime.
---
## Engines at a glance
| Engine | Architecture | Params | Per-voice cost | Quality tier |
|---|---|---|---|---|
| **`neural-28m`** | Piper VITS | ~28 M | One ONNX file per voice (~63 MB) | Standard — fast, CPU-friendly, single-thread WASM real-time on a laptop. Surfaced on Android as **Local AI Lite**, on the extension as **AI Neural CPU**. |
| **`neural-15m`** | KittenTTS-nano VITS | ~15 M | Single fp16 model + 8 speaker embeddings (one ~26 MB file serves all) | Sweet spot — 8 voices with style-vector switching at a fraction of the storage cost. Android-only, surfaced as **Local AI Plus**. |
| **`neural-82m`** | Kokoro StyleTTS2 | ~82 M | Single model + 256-dim style vectors per voice (one ~325 MB file serves all) | Premium — more natural prosody, GPU-accelerated on Chrome (WebGPU); CPU-only on Android (perf-gated). Surfaced on Android as **Local AI Studio**, on the extension as **AI Neural GPU**. |
---
## License
This repository **mirrors** upstream models for distribution stability. Each upstream project retains its own license:
- **Kokoro-82M:** Apache-2.0 ([upstream model card](https://huggingface.co/hexgrad/Kokoro-82M))
- **KittenTTS-nano (v0.1):** Apache-2.0 ([upstream model card](https://huggingface.co/KittenML/kitten-tts-nano-0.1))
- **Piper voices:** MIT, with individual voice attributions in each `.onnx.json`
- **transformers.js, onnxruntime-web, onnxruntime-android:** Apache-2.0
- **sherpa-onnx:** Apache-2.0
The mirror layout, READMEs, and any custom additions in this repository are licensed under MIT by [Pixel Labs](https://pixellabs.ventures).
---
## Links
- 🌐 ThreadCast: [threadcast.app](https://threadcast.app)
- 🧑💻 Pixel Labs: [pixellabs.ventures](https://pixellabs.ventures)
- 🐦 Issues / questions: open an issue on the [ThreadCast extension repo](https://threadcast.app/support)
|