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

# Introduction

> Low-latency, high-quality Text-to-Speech and Speech-to-Text API

This documentation covers the Gradium API.

This API exposes our Text-To-Speech and Speech-To-Text models, which offers low-latency, high-quality & natural sounding output and best in class accuracy.

For issues, questions, or feature requests, please contact us at [support@gradium.ai](mailto:support@gradium.ai)

## Features

* **Multilingual**: We currently support five languages: English (en), French (fr), German (de), Spanish (es) and Portuguese (pt) for our Text-To-Speech and Speech-To-Text with more languages to come.
* **Low-latency**: Our servers are based in Europe and in the US, with our expected time-to-first-token is below 300ms when streaming.
* **Voice selection**: We provide a voice library, with multiple voices to choose from in different languages. You can also clone voices instantaneously using a 10'' voice sample.
* **Semantic VAD**: STT streams include `step` messages every 80 ms with inactivity probabilities across future horizons, so voice agents can decide when a speaker has actually finished.
* **Adaptive delay control**: Tune `delay_in_frames` for the latency/quality tradeoff and use `flush` at turn boundaries to process buffered audio without waiting for natural silence.

<CardGroup cols={2}>
  <Card title="Installation" icon="download" href="/guides/installation">
    Get started with the Gradium Python SDK
  </Card>

  <Card title="Text-to-Speech" icon="volume-high" href="/guides/text-to-speech">
    Convert text to natural-sounding speech
  </Card>

  <Card title="Speech-to-Text" icon="microphone" href="/guides/speech-to-text">
    Transcribe audio to text in real-time
  </Card>

  <Card title="API Reference" icon="code" href="/api-reference/introduction">
    Explore the full API reference
  </Card>
</CardGroup>