> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Rapida

> Build voice agents on Rapida using Smallest AI TTS and STT.

This guide walks you through configuring [Smallest AI](https://smallest.ai) as the TTS and STT provider in [Rapida](https://rapida.ai), an open-source voice AI orchestration platform you can self-host or run managed. Rapida lets you pick a provider independently per capability - use Smallest AI for both TTS and STT, or mix it with other providers.

## Prerequisites

* A [Rapida](https://rapida.ai) instance - self-hosted (see the [voice-ai repository](https://github.com/rapidaai/voice-ai)) or managed
* A Smallest AI API key - get one from the [Smallest AI dashboard](https://waves.smallest.ai)

---

## Setup

#### Open Providers and Models

In the Rapida dashboard, navigate to **Providers and Models**.

#### Add a Smallest AI credential

Add a new provider credential, select **Smallest AI**, and paste your API key.

#### Configure TTS

On your assistant's deployment, set the text-to-speech provider to **Smallest AI** and choose a **Model**:

* `lightning_v3.1` - standard pool, voice cloning supported, 12 languages (voices: `magnus`, `devansh`, `kartik`, `maithili`, `liam`, `avery`, and more)
* `lightning_v3.1_pro` - premium pool with curated American, British, and Indian voices (English + Hindi) (voices: `meher`, `kaitlyn`, `blake`, `sophie`, `sam`, `aviraj`, and more)

The **Voice** dropdown is scoped to whichever model you picked - Pro voices aren't offered under `lightning_v3.1` and vice versa, so a mismatched pairing isn't selectable from the UI in the first place. Set the **Language**, and optionally a **Speed** (0.5–2.0).

#### Configure STT

Set the speech-to-text provider to **Smallest AI**. The **Model** is `pulse` - Rapida's integration streams over Pulse's realtime WebSocket, so `pulse-pro` (pre-recorded/HTTP-only) isn't offered here. Set the **Language**, or leave it unset for auto-detect.

Optional feature toggles are also available - word/sentence timestamps, speaker diarization, PII/PCI redaction, inverse text normalization, and punctuation formatting. See the Configuration Reference below.

---

## Configuration Reference

Rapida stores provider options as `listen.*` (STT) / `speak.*` (TTS) keys.

| Key                          | Provider | Default                   | Description                                                                                           |
| ---------------------------- | -------- | ------------------------- | ----------------------------------------------------------------------------------------------------- |
| `listen.model`               | STT      | `pulse`                   | Streaming model - only `pulse` is wired to the realtime endpoint                                      |
| `listen.language`            | STT      | auto-detect               | ISO language code (e.g. `en`, `hi`)                                                                   |
| `listen.word_timestamps`     | STT      | off                       | Per-word start/end/confidence timing                                                                  |
| `listen.sentence_timestamps` | STT      | off                       | Sentence-level utterance segments                                                                     |
| `listen.diarize`             | STT      | off                       | Speaker labels on words/utterances                                                                    |
| `listen.redact_pii`          | STT      | off                       | Redacts names, addresses, phone numbers as `[ENTITYTYPE_N]` placeholders                              |
| `listen.redact_pci`          | STT      | off                       | Redacts card numbers, CVVs, ZIP codes, account numbers                                                |
| `listen.numerals`            | STT      | provider default (`auto`) | Inverse text normalization mode                                                                       |
| `listen.smart_format`        | STT      | provider default (`true`) | Punctuation/capitalization in the transcript (Smallest's `format` param)                              |
| `speak.model`                | TTS      | `lightning_v3.1`          | `lightning_v3.1` or `lightning_v3.1_pro`                                                              |
| `speak.voice.id`             | TTS      | `magnus`                  | Catalog voice or cloned voice (`voice_*`), scoped to the selected model in the dashboard dropdown     |
| `speak.language`             | TTS      | `en`                      | Language code - see the [Lightning voices & languages guide](/models/text-to-speech/voices-languages) |
| `speak.speed`                | TTS      | `1.0`                     | Speech speed multiplier (0.5–2.0)                                                                     |

All seven `listen.*` feature flags are opt-in - Rapida only sends them to Smallest when explicitly set, so behavior is unchanged if you don't touch them.

## Notes

* Rapida routes TTS requests to `wss://api.smallest.ai/waves/v1/tts/live` and STT requests to `wss://api.smallest.ai/waves/v1/pulse/get_text`.
* Interruptions are handled by Rapida's pipeline: on barge-in, the TTS connection is closed and reopened for the next turn - no custom logic needed on the Smallest AI side.
* If a `speak.voice.id`/`speak.model` pairing the API doesn't support is sent (e.g. a Pro-only voice with `lightning_v3.1`), Rapida surfaces it as an error on that turn rather than hanging - the dashboard's model-scoped voice dropdown is the main safeguard, this is the fallback for free-typed voice IDs.
* For issues with the Smallest AI integration in Rapida, open an issue in the [Rapida repository](https://github.com/rapidaai/voice-ai) or contact us on [Discord](https://discord.gg/9WtSXv26WE).

> Build voice agents on Rapida using Smallest AI TTS and STT.