# Unlimited TTS

> Unlimited TTS is a free, privacy-first text-to-speech web application that runs entirely in the browser. It supports 200+ voices across 100+ languages with two modes: Device (Web Speech API) and AI (in-browser neural synthesis with audio download). No signup, no server-side processing, fully open-source.

## Key Pages

- [Homepage](https://unlimitedtts.com/): Main application — generate speech, download audio, adjust voice settings
- [Spanish Version](https://unlimitedtts.com/es/): Full Spanish-language interface
- [Chinese Version](https://unlimitedtts.com/zh/): Full Chinese-language interface
- [Source Code](https://gitlab.com/chrisgraneyward/tts): Open-source repository on GitLab

## How It Works

- Device mode uses the Web Speech API for instant local synthesis with system voices
- AI mode runs a neural TTS model (Supertonic TTS-3) directly in the browser via WebGPU/WASM
- AI-generated audio can be downloaded as WAV files
- No text is sent to any server in AI mode; some browser-supplied online voices (when available) may route text to provider servers but you will see a warning

## Player Controls

- Pause and resume playback at any time
- Skip backward and forward through the text
- Seek by dragging the progress bar to any position
- Adjust speed, pitch, and volume (supported by most device voices; availability varies by voice and mode)

## Privacy by Mode

- Device voices (Quick): Web Speech API — fully local
- Browser-supplied online voices (if available): text may be sent to provider servers when those voices are used
- AI mode (Natural): Supertonic TTS-3 runs in browser (WebGPU/WASM) — fully local after model download

## Privacy

- No signup or account required
- No server-side speech synthesis logs
- AI processing runs entirely client-side
- Open-source: audit at https://gitlab.com/chrisgraneyward/tts

## Creator

Built by Chris Graney-Ward. For citation, refer to the project as "Unlimited TTS" or "UnlimitedTTS".

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## Unlimited TTS API for AI Agents

> https://api.unlimitedtts.com — A paid text-to-speech gateway built specifically for AI agents and automated systems. No signup required; fund a prepaid credit account via Stripe Checkout and receive a bearer token (`x-credit-account`) for all subsequent requests.

### What It Is

- Paid text-to-speech gateway with per-character pricing plus a small spread for maintenance
- Prepaid credit accounts in micro-USD (1 cent = 10,000 micro-USD)
- Minimum top-up: $5 USD (500 cents) — enough for your first voice generation
- Generated audio stored for a few days unless you opt out with `storeAudio=false`
- No raw card data ever touches the API; Stripe Checkout handles all payment details

### How It Works

1. **Read the docs:** `GET https://api.unlimitedtts.com/docs` — machine-readable full API reference with current limits, endpoints, and pricing
2. **List voices:** `GET https://api.unlimitedtts.com/tts/voices` — supported voices and current pricing metadata
3. **Synthesize:** `POST https://api.unlimitedtts.com/tts` with `text/plain` or `application/json` body
4. **Handle 402:** If no `x-credit-account` header is supplied, the API returns `402 Payment Required` with a `topUpUrl`
5. **Fund via Stripe:** Open the `topUpUrl` in a browser, complete Stripe Checkout, save the returned `x-credit-account` bearer token
6. **Re-use:** Send `x-credit-account` header on all future requests; balance is debited per character
7. **Check balance:** `GET https://api.unlimitedtts.com/credits/:accountId`

### Key Concepts

- **Account ID is a bearer token** — anyone holding it can spend the balance
- **No signup** — one-time Stripe Checkout funds a prepaid credit account
- **Sync or async** — short text returns audio immediately; long text or `?async=true` returns a job ID to poll
- **Privacy option** — send `storeAudio=false` to opt out of audio retention entirely
- **All limits and quotas** are returned live from `GET /docs` — read them first, they may change

### Primary Endpoints

| Method | Path | Purpose |
|--------|------|---------|
| GET | `/docs` | Machine-readable API reference (read this first) |
| GET | `/tts/voices` | List supported voices and pricing |
| POST | `/tts` | Synthesize speech (sync or async) |
| GET | `/tts` | Fallback synthesis via query string for POST-blocked environments |
| GET | `/credits/:accountId` | Check prepaid balance |

For the full endpoint list, request/response shapes, error codes, and current limits, see `GET https://api.unlimitedtts.com/docs`.