> ## 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 and JavaScript.

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 zeroruntime import Pipeline
  from zeroruntime.plugins import OpenAIRealtime

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

  pipeline = Pipeline(llm=model)
  ```

  ```typescript Node JS theme={null}
  import { Pipeline } from '@zeroruntime/js-sdk';
  import { OpenAIRealtime } from '@zeroruntime/js-sdk/plugins';

  const model = OpenAIRealtime({
    model: 'gpt-4o-realtime-preview',
    config: {
      voice: 'alloy',
      modalities: ['text', 'audio'],
    },
  });

  const pipeline = Pipeline({ llm: model });
  ```
</CodeGroup>

## Configuration

*`OpenAIRealtime` constructor and `config` keys in both SDKs. The Python and Node JS SDKs share these field names.*

### Constructor

| Parameter | Type   | Default                     | Description                                                                         |
| --------- | ------ | --------------------------- | ----------------------------------------------------------------------------------- |
| `model`   | `str`  | `"gpt-4o-realtime-preview"` | Realtime model ID.                                                                  |
| `api_key` | `str`  | `None`                      | OpenAI API key. Falls back to the `OPENAI_API_KEY` environment variable when unset. |
| `config`  | `dict` | `None`                      | Model behavior configuration (see below).                                           |

### `config` keys

| Field                       | Type                            | Default                  | Description                                                                                                                     |
| --------------------------- | ------------------------------- | ------------------------ | ------------------------------------------------------------------------------------------------------------------------------- |
| `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 zeroruntime.plugins import OpenAIRealtime`               | `OpenAIRealtime(model=..., config={...})` |
| Node JS | `import { OpenAIRealtime } from '@zeroruntime/js-sdk/plugins'` | `OpenAIRealtime({ ... })`                 |

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