---
title: HF Realtime Voice
emoji: 🎙️
colorFrom: indigo
colorTo: purple
sdk: docker
app_port: 7860
pinned: false
short_description: Voice chat over WebSocket against a HF speech-to-speech
hf_oauth: true
---

# Realtime voice backend and retained static client

FastAPI server and retained static voice-chat UI for an OpenAI Realtime-compatible
speech-to-speech backend. The browser streams microphone audio over WebSocket,
plays assistant audio, displays transcripts, and offers Spanish controls.

The root `start_ui.sh` now serves the [React frontend](../s2s-frontend) with
Vite on public port `8420`, proxying backend requests here on loopback port
`8421`. This directory's static UI remains available when FastAPI is run
directly or through the existing Docker image.

The complete [usage guide](../docs/client/usage.md) covers local startup,
connection modes, Docker, settings, and usage limits. See the
[documentation index](../docs/README.md), [architecture](../docs/client/architecture.md),
and [change history](CHANGELOG.md) for implementation details and history.

The retained static client's assistant replies render Markdown with Marked and
DOMPurify. Their pinned, checked-in browser modules are served from `vendor/`, including upstream
licenses, so the UI does not require a CDN or a Node.js runtime. To refresh the
browser dependencies with Node.js 20 or newer after updating `package.json`:

```bash
cd s2s-client
npm install --ignore-scripts
npm run vendor
```

Commit `package-lock.json` and the generated `vendor/` files together. Existing
locked versions can be restored with `npm ci --ignore-scripts`.

Build from the repository root so the container includes the documentation:

```bash
docker build -f s2s-client/Dockerfile -t s2s-client .
```

FastAPI's API explorer remains at `/docs`. Project documents are served as files below
`/docs/client/`, `/docs/speech/`, `/docs/adr/`, `/docs/examples/`, and
`/docs/proposals/`. The historical `/project/` and `/public/docs.html` URLs
redirect to the retained architecture proposal. Markdown remains source text;
documentation directories are not browsable rendered pages. Start from the
repository documentation index or request `/docs/README.md` explicitly.