otoji (音字)

realtime speech ⇄ text — 音を字に

otoji.org — wire mic → STT → translate → speech as a voice graph that runs on your devices. No accounts, no API keys, nothing leaves the browser by default: ASR, translation, and TTS all run on-device (transformers.js / onnxruntime-web / WebGPU / WASM).

Join a room and the graph spans your devices: a phone captures the mic, a laptop runs SenseVoice, any device speaks the result — chained over a WebRTC P2P mesh, Google-Meet-style shareable URLs (otoji.org/keen-gibbon-4a0d).

   phone                         laptop                        any device
 ┌─────────┐   opus/segment    ┌──────────────┐   transcript  ┌──────────┐
 │ Mic+VAD ├══════════════════>│ SenseVoice    ├═════════════>│ Translate │──► 🔊 / 📝 / .srt
 └─────────┘   WebRTC (P2P)    │ STT           │   WebRTC      └──────────┘
                               └──────────────┘

Try it

• otoji.org — create/join a room, or hit "Try it here" to run the whole graph locally on one device (no room needed).
• otoji.org/?simple — minimal one-box live transcription, no graph editor.

How it works

Each node has typed ports — segment (audio) or transcript (text) — and an edge is valid only when the source output type matches the target input type. Same-device edges run in-process; cross-device edges become a WebRTC data channel carrying audio segments + transcript frames. The graph itself is authoritative state, synced live to every device in the room through a Cloudflare Durable Object (the only server; it relays signaling + graph patches, never your audio).

Node catalog

| Category | Nodes | |---|---| | Input | Mic + VAD · Mic (raw, no VAD) · Audio file in (drop or URL) · Text file in | | Speech → Text | SenseVoice STT (ONNX, multilingual + emotion/event tags) · Web Speech (browser streaming) · Vosk (Kaldi/WASM streaming) | | Text → Text | Translate — in-browser LLM (WebLLM) or the browser Translator API | | Text → Speech | Text-to-Speech (browser SpeechSynthesis) · Neural TTS (on-device ONNX MMS-TTS) | | Output | Transcript + Recordings · Audio file (out) · SRT subtitles (out) · Speaker (play) | | Custom | Any transformers.js model by repo/URL (ASR / text2text / TTS) | | Pipe | CLI stdio bridge — wire a terminal into the graph via otoji node; see CLI pipe recipes |

Models download once per device and can be shared P2P within a room, so only one device pays the download cost.

Local-first

Everything runs locally by default — no API keys, no cloud, no internet. Cloud providers (Anthropic / OpenAI / iFlytek / ElevenLabs / Gemini) are opt-in fallbacks you can configure with your own keys, stored only in your browser. Resolution order for every component: local in-process > local server > cloud API > disabled. See docs/ROADMAP.md.

CLI: bridge a terminal into a graph

The CLI pipe node bridges any terminal's stdio to the graph over the signaling relay (no WebRTC needed) — copy the command shown on the node:

npx otoji node otoji.org/keen-gibbon-4a0d/pipe-ab12   # text in graph → stdout; stdin → graph
otoji node my-room | grep foo                          # consume transcripts
some-producer | otoji node my-room                     # feed text in

@otoji/core — Node/Bun bindings

The Rust core also ships as an npm package with napi-rs bindings for one-shot and streaming on-device SenseVoice:

import { transcribe, listen } from "@otoji/core";

const { text } = await transcribe("meeting.wav");      // one-shot

const session = listen({                               // streaming
  onPartial: (t) => process.stdout.write(`\r${t}`),
  onFinal:   (t) => console.log(`\n✓ ${t}`),
});
session.push(pcmFloat32);                               // 16kHz mono f32
await session.end();

Repository layout

| Path | What | |---|---| | web/ | The otoji.org app — React Flow voice-graph editor, WebRTC mesh, on-device providers, plus a browser extension + userscript | | signal/ | Cloudflare Worker + RoomDurableObject — presence, SDP/ICE relay, authoritative graph state | | src/ | Rust core — SenseVoice ASR, VAD, TTS, LLM polish; cpal/ratatui desktop CLI; napi bindings | | cli/otoji-node.mjs | otoji node — the stdio↔graph bridge | | docs/ | Architecture rationale, RT-ASR/model benchmarks, roadmap |

See TODO.md for the distributed voice-graph design and milestone status, and docs/ for the deeper architecture/benchmark notes.

Develop

# Web app
cd web && bun install && bun run dev        # http://localhost:5173
bun run test                                # vitest
bun run test:e2e                            # playwright

# Rust core / desktop CLI
cargo build --release
cargo run -- listen                         # live mic → on-device STT in the TUI

License

MIT