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

# API Reference

Pick a product to jump to its full API reference. Each product tab has its own reference section with all endpoints, request and response schemas, and example calls.

<CardGroup cols={2}>
  <Card title="Pre-recorded STT" icon="file-audio" href="/docs/pre-recorded-audio/api-reference/files/upload">
    Get clean, customizable transcripts in 99 languages with industry-leading accuracy and natural language prompting.
  </Card>

  <Card title="Real-time STT" icon="waveform-lines" href="/docs/streaming/api-spec/streaming-websocket">
    Real-time transcription your notetaker, agents, and captions can depend on.
  </Card>

  <Card title="Sync STT" icon="bolt" href="/docs/api-reference/sync-api/transcribe">
    Send an audio file in a single HTTP request, get a transcript back in milliseconds. No polling, no session management.
  </Card>

  <Card title="LLM Gateway" icon="messages" href="/docs/llm-gateway/api-reference/create-chat-completion">
    One OpenAI-compatible API for every frontier model — with automatic fallbacks, zero markup, and zero data retention.
  </Card>

  <Card title="Voice Agent API" icon="headset" href="/docs/voice-agents/voice-agent-api/api-spec/voice-agent-websocket">
    Stream audio in, get audio back. We handle the rest so you can focus on your product.
  </Card>
</CardGroup>