WebRTC vs WebSockets vs SSE for AI Streaming: Choosing the Right Protocol

Overview #

A technical protocol comparison between Server-Sent Events (SSE), WebSockets, and WebRTC for delivering real-time streaming tokens, multimodal bi-directional data, and sub-300ms voice interactions in production AI applications.

Server-Sent Events (SSE): The Standard for Text Streaming #

SSE operates over standard HTTP/1.1 or HTTP/2. The client sends a standard POST request, and the server keeps the connection open, emitting data: { ... } chunks. SSE is simple, firewall-friendly, natively supported by browser EventSource, and automatically handles reconnects. It is the universal standard for LLM text completion streams.

WebSockets: Full-Duplex Bi-Directional Communication #

When an application requires continuous bi-directional messaging (such as streaming audio chunks while simultaneously receiving tokens, or passing live cursor telemetry), WebSockets provides a persistent TCP socket. However, WebSockets requires custom reconnection logic, does not multiplex over HTTP/2, and faces proxy timeout challenges in corporate firewalls.

WebRTC: Ultra-Low Latency UDP Media Streaming #

For real-time voice and video conversations, TCP's retransmission delays (head-of-line blocking) cause audible stuttering on mobile networks. WebRTC uses UDP and SRTP encryption, prioritizing timeliness over 100% packet delivery to achieve natural human conversation with sub-300ms latency.

Code Example: Protocol Selection Matrix in System Design #

type AIInteractionType = "text_chat" | "code_streaming" | "voice_agent" | "live_video";

function recommendProtocol(type: AIInteractionType): string {
  switch (type) {
    case "text_chat":
    case "code_streaming":
      return "Server-Sent Events (SSE) - HTTP/2 standard, firewall friendly";
    case "voice_agent":
    case "live_video":
      return "WebRTC Data & Media Channels - Sub-300ms UDP transport";
    default:
      return "Standard HTTPS REST";
  }
}

console.log(recommendProtocol("voice_agent"));

Frequently Asked Questions #

Q: Why do OpenAI and Anthropic use SSE instead of WebSockets for text?

SSE works over standard HTTP/2, natively supports edge CDN routing, bypasses proxy blocks, and requires no protocol upgrade handshakes.

Q: Can SSE carry binary data?

SSE is text-based (UTF-8). Binary data must be base64-encoded, which incurs a 33% bandwidth overhead. WebSockets or WebRTC are preferred for raw binary audio/video.

Q: Does HTTP/2 multiplexing work with SSE?

Yes, over HTTP/2, multiple SSE streams can share a single underlying TCP connection, preventing the 6-connection limit per domain found in HTTP/1.1.