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

# OpenAI Realtime

> Use the OpenAI Realtime speech-to-speech model in a Zero Runtime pipeline. Setup, options, and usage in Python, JavaScript, and Go.

OpenAI Realtime is a **speech-to-speech** model. It handles transcription, reasoning, and
voice synthesis end-to-end in a single model, so it goes in the pipeline's `llm` slot with
no separate STT or TTS. The `Pipeline` auto-detects [Realtime mode](/build/configure-a-pipeline/modes)
when you pass it.

## Setup

Set your OpenAI API key in the worker environment. Generate a key from the [OpenAI dashboard](https://platform.openai.com/api-keys):

```bash theme={null}
export OPENAI_API_KEY=<key>
```

## Usage

Pass the realtime model to the pipeline's `llm` slot, no `stt` or `tts` needed.

<CodeGroup>
  ```python Python theme={null}
  from zrt import Pipeline
  from zrt.plugins import OpenAIRealtime, OpenAIRealtimeConfig

  model = OpenAIRealtime(
      config=OpenAIRealtimeConfig(
          model="gpt-4o-realtime-preview",
          voice="alloy",
          modalities=["text", "audio"],
      ),
  )

  pipeline = Pipeline(llm=model)
  ```
</CodeGroup>

## Configuration

*`OpenAIRealtime` constructor and `OpenAIRealtimeConfig` fields for the Python SDK. The JavaScript SDK passes the same settings via the flat `config` object; the Go SDK via `RealtimeOptions`.*

### Constructor

| Parameter | Type                   | Default | Description                                                                         |
| --------- | ---------------------- | ------- | ----------------------------------------------------------------------------------- |
| `api_key` | `str`                  | `None`  | OpenAI API key. Falls back to the `OPENAI_API_KEY` environment variable when unset. |
| `config`  | `OpenAIRealtimeConfig` | `None`  | Model behavior configuration (see below).                                           |

### `OpenAIRealtimeConfig`

| Field                       | Type                            | Default                     | Description                                                                                                                     |
| --------------------------- | ------------------------------- | --------------------------- | ------------------------------------------------------------------------------------------------------------------------------- |
| `model`                     | `str`                           | `"gpt-4o-realtime-preview"` | Realtime model ID.                                                                                                              |
| `voice`                     | `str`                           | `"alloy"`                   | Output voice (e.g. `alloy`, `ash`, `marin`, `cedar`, `verse`).                                                                  |
| `temperature`               | `float`                         | `0.8`                       | Sampling randomness.                                                                                                            |
| `turn_detection`            | `TurnDetectionConfig`           | server VAD                  | Turn detection (`server_vad`, threshold `0.5`, `prefix_padding_ms` `300`, `silence_duration_ms` `200`). Pass `None` to disable. |
| `input_audio_transcription` | `InputAudioTranscriptionConfig` | `gpt-4o-mini-transcribe`    | Transcription model for the user's audio.                                                                                       |
| `tool_choice`               | `str`                           | `"auto"`                    | How the model decides when to call tools.                                                                                       |
| `modalities`                | `list[str]`                     | `["text", "audio"]`         | Enabled response modalities. Drop `"audio"` for text-only.                                                                      |

## Import paths

| SDK        | Import                                                         | Constructor                                                         |
| ---------- | -------------------------------------------------------------- | ------------------------------------------------------------------- |
| Python     | `from zrt.plugins import OpenAIRealtime, OpenAIRealtimeConfig` | `OpenAIRealtime(config=...)`                                        |
| JavaScript | `from '@zrt/js-sdk/plugins/openai_realtime'`                   | `OpenAIRealtime({ config: { ... } })`                               |
| Go         | `.../zrt-golang-sdk/plugins/openai_realtime`                   | `openai_realtime.NewRealtime(openai_realtime.RealtimeOptions{...})` |

To pair the realtime model with an external STT or TTS, see
[Hybrid mode](/build/configure-a-pipeline/modes#hybrid).