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

# Overview: Ultravox Realtime

> Build Voice AI Agents That Work Anywhere

<CardGroup cols={4}>
  <Card title="Sign-up" icon="user-plus" iconType="duotone" color="009edc" href="https://app.ultravox.ai?utm_source=docs" />

  <Card title="Quickstart" icon="person-running-fast" iconType="duotone" color="ff936f" href="/gettingstarted/quickstart/agent-console" />

  <Card title="API Reference + Playground" icon="code" iconType="duotone" color="ff5f6d" href="api-reference" />
</CardGroup>

## Key Features

Built on our best-in-class, [open-weight model](https://github.com/fixie-ai/ultravox), Ultravox Realtime provides a fully hosted platform for creating real-time, low-latency voice AI applications.

We provide everything you need:

<Icon icon="language" size={24} /> **Multi-lingual** → Support for 26 spoken languages (Arabic, Bulgarian, Chinese, Czech, Danish, Dutch, English, Finnish, French, German, Greek, Hindi, Hungarian, Italian, Japanese, Polish, Portuguese, Romanian, Russian, Slovak, Spanish, Swedish, Tamil, Turkish, Ukrainian, Vietnamese)

<Icon icon="toolbox" size={24} /> [**Tools**](/tools/overview) → Give your agent the ability to connect to the world (AKA function calling)

<Icon icon="book" size={24} /> [**Knowledge (RAG)**](/tools/rag) → Amp up your agent's knowledge with custom, contextual knowledge

<Icon icon="arrow-progress" size={24} /> [**Call Stages**](/agents/call-stages) → Advanced agent branching and flows

<Icon icon="clock-rotate-left" size={24} /> [**Conversation History**](/api-reference/calls/calls-messages-list) → Audio recordings and full text transcripts

<Icon icon="circle-microphone" size={24} /> [**Voice Cloning**](/voices/overview) → Create the perfect voice for your agent

<Icon icon="code" size={24} /> [**SDKs**](/apps/sdks) → Build in your favorite language

<Icon icon="phone-plus" size={24} /> [**Telephony Integrations**](/telephony/overview) → Quickly use Ultravox with telephony partners

<Icon icon="webhook" size={24} /> [**Webhooks**](/webhooks/overview) → Get realtime notifications for key events