> ## Documentation Index
> Fetch the complete documentation index at: https://doc.rapida.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Smallest AI TTS

> Configure Smallest AI Lightning text-to-speech in assistant-api.

Smallest AI's Lightning models stream over a realtime WebSocket with \~100ms to first audio chunk. `lightning_v3.1` covers 12 languages with voice cloning; `lightning_v3.1_pro` is a premium voice pool (American, British, and Indian accents) selected per-request via the same connection.

**Provider identifier:** `smallest`

***

## Vault Credential

| Key   | Description                                                                             |
| ----- | --------------------------------------------------------------------------------------- |
| `key` | Smallest AI API key from [app.smallest.ai/dashboard](https://app.smallest.ai/dashboard) |

***

## Setup

<Steps>
  <Step title="Get a Smallest AI API key">
    Sign in at [app.smallest.ai/dashboard](https://app.smallest.ai/dashboard) → **Developer → API Keys**.
  </Step>

  <Step title="Add to Rapida vault">
    In the Rapida dashboard → **Providers and Models**, add a credential, select provider **Smallest AI**, enter `key` = your API key.

    The same credential is used for both Smallest AI STT and TTS.
  </Step>

  <Step title="Configure the assistant">
    In the assistant's deployment settings → **Audio Output (TTS)**, select **Smallest AI** and pick a **Model**:

    * `lightning_v3.1` — standard pool, voice cloning supported, 12 languages
    * `lightning_v3.1_pro` — premium pool with curated American, British, and Indian accented voices (English + Hindi)

    | Option           | Example          | Description                                                                                                                       |
    | ---------------- | ---------------- | --------------------------------------------------------------------------------------------------------------------------------- |
    | `speak.model`    | `lightning_v3.1` | `lightning_v3.1` or `lightning_v3.1_pro`                                                                                          |
    | `speak.voice.id` | `magnus`         | Catalog voice, scoped to the selected model — Pro-only voices (e.g. `meher`) aren't offered under `lightning_v3.1` and vice versa |
    | `speak.language` | `en`             | Language code — Pro supports a broader set than standard                                                                          |
    | `speak.speed`    | `1.0`            | Speech speed multiplier (0.5–2.0)                                                                                                 |

    Pairing a voice with the wrong model pool is rejected by the API — the provider surfaces this as an error rather than hanging or producing garbled audio.
  </Step>
</Steps>

***

<CardGroup cols={2}>
  <Card title="Smallest AI STT" icon="audio-waveform" href="/opensource/services/assistant-api/stt/smallest">
    Smallest AI Pulse speech-to-text
  </Card>

  <Card title="TTS Overview" icon="volume" href="/opensource/services/assistant-api/tts/overview">
    All TTS providers
  </Card>
</CardGroup>