> ## 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.

# ElevenLabs

> Use the ElevenLabs text-to-speech plugin in a Zero Runtime pipeline. Setup, options, and usage in Python and JavaScript.

ElevenLabs is a **text-to-speech** plugin. It synthesizes the LLM's reply into the agent's
voice, streaming low-latency audio over a WebSocket. It occupies the pipeline's `tts` slot.

## Setup

Set your ElevenLabs API key in the worker environment. Generate a key from the [ElevenLabs dashboard](https://elevenlabs.io/app/settings/api-keys):

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

## Usage

Import the plugin and pass it to the pipeline's `tts` slot.

<CodeGroup>
  ```python Python theme={null}
  from zeroruntime.plugins import ElevenLabsTTS

  tts = ElevenLabsTTS(
      model="eleven_turbo_v2",
      voice="21m00Tcm4TlvDq8ikWAM",
  )

  # Pipeline(tts=tts, ...)
  ```

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

  const tts = ElevenLabsTTS({
    model: 'eleven_turbo_v2',
    voice: '21m00Tcm4TlvDq8ikWAM',
  });

  // Pipeline({ tts, ... })
  ```
</CodeGroup>

<Note>
  Both SDKs default to model `eleven_turbo_v2` and voice `21m00Tcm4TlvDq8ikWAM`
  (the "Rachel" voice). Pass `model` and `voice` explicitly for consistent results across SDKs.
</Note>

## Voice settings

Fine-tune the voice with the `voice_settings` mapping, which mirrors ElevenLabs'
native `voice_settings` shape: `stability`, `similarity_boost`, `style` and
`use_speaker_boost`.

<CodeGroup>
  ```python Python theme={null}
  from zeroruntime.plugins import ElevenLabsTTS

  tts = ElevenLabsTTS(
      voice_settings={
          "stability": 0.5,
          "similarity_boost": 0.75,
          "style": 0.0,
          "use_speaker_boost": True,
      },
  )
  ```

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

  const tts = ElevenLabsTTS({
    voice_settings: {
      stability: 0.5,
      similarity_boost: 0.75,
      style: 0.0,
      use_speaker_boost: true,
    },
  });
  ```
</CodeGroup>

## Parameters

*Constructor parameters for `ElevenLabsTTS`. The Python and Node JS SDKs share these field names.*

| Parameter | Type | Default | Description |
| - | - | - | - |
| `api_key` | `str` | `None` | ElevenLabs API key. Falls back to the `ELEVENLABS_API_KEY` environment variable when unset. |
| `voice` | `str` | `"21m00Tcm4TlvDq8ikWAM"` | Voice ID (the "Rachel" voice). |
| `model` | `str` | `"eleven_turbo_v2"` | ElevenLabs synthesis model (`eleven_v3`, `eleven_multilingual_v2`, `eleven_flash_v2_5`, `eleven_flash_v2`). |
| `sample_rate` | `int` | `24000` | Output sample rate in Hz. |
| `stability` | `float` | `0.5` | Voice consistency, 0.0-1.0 (higher is steadier). |
| `similarity_boost` | `float` | `0.75` | Adherence to the original voice, 0.0-1.0. |
| `style` | `float` | `0.0` | Style exaggeration, 0.0-1.0 (0 disables, adds latency). |
| `use_speaker_boost` | `bool` | `True` | Boost similarity to the speaker. |
| `apply_text_normalization` | `str` | `None` | Text normalization mode: `"auto"`, `"on"`, or `"off"`. |
| `enable_word_timestamps` | `bool` | `False` | Return per-word timing metadata. |
| `speed` | `float` | `None` | Speaking-rate multiplier (\~0.7-1.2). Provider default when unset. |
| `language` | `str` | `None` | ISO-639-1 language hint for supported models. |
| `enable_ssml_parsing` | `bool` | `None` | Interpret SSML tags in the input text. |
| `stream` | `bool` | `True` | Stream audio as it is synthesized. |

## Import paths

| SDK | Import | Constructor |
| - | - | - |
| Python | `from zeroruntime.plugins import ElevenLabsTTS` | `ElevenLabsTTS(...)` |
| Node JS | `import { ElevenLabsTTS } from '@zeroruntime/js-sdk/plugins'` | `ElevenLabsTTS({ ... })` |

The synthesized audio is streamed back to the caller as the final stage of the
[pipeline](/runtime-sdk/build/configure-a-pipeline).


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