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

# Smallest AI

> Speech-to-text service using Smallest AI's Pulse WebSocket API

## Overview

Smallest AI provides real-time speech-to-text transcription through a WebSocket-based integration with their Waves API. The service uses the Pulse model to stream audio continuously and receive interim and final transcription results with low latency.

<CardGroup cols={2}>
  <Card title="Smallest AI STT API Reference" icon="code" href="https://reference-server.pipecat.ai/en/latest/api/pipecat.services.smallest.stt.html">
    Complete API reference for all parameters and methods
  </Card>

  <Card title="Example Implementation" icon="play" href="https://github.com/pipecat-ai/pipecat/blob/main/examples/voice/voice-smallest.py">
    Complete example with WebSocket streaming
  </Card>
</CardGroup>

## Installation

```bash theme={null}
uv add "pipecat-ai[smallest]"
```

## Prerequisites

1. **Smallest AI Account**: Sign up at [Smallest AI](https://www.smallest.ai/)
2. **API Key**: Generate an API key from your account dashboard

Set the following environment variable:

```bash theme={null}
export SMALLEST_API_KEY=your_api_key
```

## Configuration

<ParamField path="api_key" type="str" required>
  Smallest AI API key for authentication.
</ParamField>

<ParamField path="base_url" type="str" default="wss://api.smallest.ai">
  Base WebSocket URL for the Smallest API. Override for custom or proxied
  deployments.
</ParamField>

<ParamField path="encoding" type="str" default="linear16">
  Audio encoding format.
</ParamField>

<ParamField path="sample_rate" type="int" default="None">
  Audio sample rate in Hz. When `None`, uses the pipeline's configured sample
  rate.
</ParamField>

<ParamField path="settings" type="SmallestSTTService.Settings" default="None">
  Runtime-configurable settings. See [Settings](#settings) below.
</ParamField>

<ParamField path="ttfs_p99_latency" type="float" default="SMALLEST_TTFS_P99">
  P99 latency from speech end to final transcript in seconds. Used for
  processing metrics.
</ParamField>

### Settings

Runtime-configurable settings passed via the `settings` constructor argument using `SmallestSTTService.Settings(...)`. These can be updated mid-conversation with `STTUpdateSettingsFrame`. See [Service Settings](/guides/fundamentals/service-settings) for details.

| Parameter             | Type              | Default       | Description                                                              |
| --------------------- | ----------------- | ------------- | ------------------------------------------------------------------------ |
| `model`               | `str`             | `pulse`       | Model identifier. Currently only `pulse` is supported.                   |
| `language`            | `Language \| str` | `Language.EN` | Language code for transcription.                                         |
| `word_timestamps`     | `bool`            | `False`       | Include word-level timestamps in transcription results.                  |
| `full_transcript`     | `bool`            | `False`       | Include cumulative transcript in results.                                |
| `sentence_timestamps` | `bool`            | `False`       | Include sentence-level timestamps in transcription results.              |
| `redact_pii`          | `bool`            | `False`       | Redact personally identifiable information from transcripts.             |
| `redact_pci`          | `bool`            | `False`       | Redact payment card information from transcripts.                        |
| `numerals`            | `str`             | `auto`        | Convert spoken numerals to digits. Options: `auto`, `always`, or `none`. |
| `diarize`             | `bool`            | `False`       | Enable speaker diarization to identify different speakers.               |

## Usage

### Basic Setup

```python theme={null}
from pipecat.services.smallest.stt import SmallestSTTService
from pipecat.transcriptions.language import Language

stt = SmallestSTTService(
    api_key=os.getenv("SMALLEST_API_KEY"),
    settings=SmallestSTTService.Settings(
        language=Language.EN,
    ),
)
```

### With Advanced Features

```python theme={null}
stt = SmallestSTTService(
    api_key=os.getenv("SMALLEST_API_KEY"),
    settings=SmallestSTTService.Settings(
        language=Language.ES,
        word_timestamps=True,
        diarize=True,
        redact_pii=True,
    ),
)
```

### Updating Settings at Runtime

Transcription settings can be changed mid-conversation using `STTUpdateSettingsFrame`:

```python theme={null}
from pipecat.frames.frames import STTUpdateSettingsFrame
from pipecat.services.smallest.stt import SmallestSTTSettings

await task.queue_frame(
    STTUpdateSettingsFrame(
        delta=SmallestSTTSettings(
            language=Language.FR,
            word_timestamps=False,
        )
    )
)
```

<Tip>
  Changing settings will trigger a WebSocket reconnection, which may cause a
  brief interruption in transcription.
</Tip>

## Notes

* **WebSocket streaming**: The service uses WebSocket connections for real-time streaming. The connection is automatically managed and will reconnect if interrupted.
* **VAD integration**: Uses Pipecat's VAD to detect when the user stops speaking and sends a finalize message to flush the final transcript.
* **Keepalive**: The service sends periodic keepalive messages (every 5 seconds) to prevent idle timeouts on the WebSocket connection.
* **Language support**: Supports 31 languages including Bulgarian, Bengali, Czech, Danish, German, English, Spanish, Estonian, Finnish, French, Gujarati, Hindi, Hungarian, Italian, Kannada, Lithuanian, Latvian, Malayalam, Marathi, Maltese, Dutch, Odia, Punjabi, Polish, Portuguese, Romanian, Russian, Slovak, Swedish, Tamil, Telugu, and Ukrainian.

## Event Handlers

Smallest AI STT supports the standard [service connection events](/server/events/service-events):

| Event                 | Description                          |
| --------------------- | ------------------------------------ |
| `on_connected`        | Connected to Smallest AI WebSocket   |
| `on_disconnected`     | Disconnected from Smallest WebSocket |
| `on_connection_error` | WebSocket connection error occurred  |

```python theme={null}
@stt.event_handler("on_connected")
async def on_connected(service):
    print("Connected to Smallest AI STT")
```