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

# Introduction

> Build intelligent, low-latency voice agents with Line.

## What is Line?

Line brings voice to your text agents with Cartesia's state-of-the-art speech models. We handle audio orchestration, deployment, and observability so you can focus on your agent's reasoning.

## Get Started

<CardGroup cols={3}>
  <Card title="Quickstart" icon="rocket" href="./start-building/quickstart">
    Build, deploy, and call your first agent
  </Card>

  <Card title="Agent Builder" icon="sparkles" href="./start-building/agent-builder">
    Prototype and iterate on agents without code
  </Card>

  <Card title="SDK" icon="code" href="./sdk/overview">
    Write your custom reasoning logic in code
  </Card>
</CardGroup>

## Audio Orchestration

Line deploys your code in seconds in our managed runtime with auto-scaling and blazing fast audio processing, using [Ink](https://cartesia.ai/ink) for speech-to-text and [Sonic](https://cartesia.ai/sonic) for text-to-speech.

<Frame>
  <img src="https://mintcdn.com/cartesia-2650f86a/bcE0PrYtfJKz4Yg4/assets/images/agents/line-architecture.png?fit=max&auto=format&n=bcE0PrYtfJKz4Yg4&q=85&s=be12194015bac6c04b9f23413e785b53" alt="Line voice agent platform architecture" width="5760" height="3240" data-path="assets/images/agents/line-architecture.png" />
</Frame>

## What You Can Build

Line gives you full control over your agent's behavior through code: connect any LLM, call external APIs, query databases, and handle interruptions and turn-taking.

## Developer Tools

* **[CLI](/line/cli)** – Deploy and test agents from your terminal
* **[Call logs](/line/infrastructure/observability#call-logs)** – Debug conversations and monitor performance
* **[Evaluations](/line/evaluations/metrics)** – Measure agent quality with custom metrics
* **[Deployments](/line/infrastructure/observability#deployment)** – Track versions and roll back changes