# Server-Sent Events (SSE)

**Canonical:** https://apis.io/apis/realtime/server-sent-events/  
**Provider:** Realtime — https://apis.io/providers/realtime/  
**Base URL:** https://  
**Documentation:** https://html.spec.whatwg.org/multipage/server-sent-events.html

Server-Sent Events (SSE) is one of 26 APIs that [Realtime](https://apis.io/providers/realtime/) publishes on the [APIs.io](https://apis.io/) network. Tagged areas include SSE, Server-Sent Events, Protocol, Unidirectional, and Standard. The published artifact set on APIs.io includes API documentation.

A unidirectional server-to-client streaming protocol over HTTP, defined by the WHATWG HTML Living Standard. SSE is simpler than WebSocket — it reuses HTTP and supports automatic reconnection — but is one-way only. It has seen a resurgence as the carrier for LLM token streams from OpenAI, Anthropic, and other AI APIs.

## Machine-readable artifacts (2)

- **Specification** — https://html.spec.whatwg.org/multipage/server-sent-events.html
- **Documentation** — https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events

## Other Realtime APIs (12)

- [WebSocket](https://apis.io/apis/realtime/websocket/)
- [WebRTC](https://apis.io/apis/realtime/webrtc/)
- [MQTT](https://apis.io/apis/realtime/mqtt/)
- [CoAP](https://apis.io/apis/realtime/coap/)
- [gRPC Streaming](https://apis.io/apis/realtime/grpc-streaming/)
- [GraphQL Subscriptions](https://apis.io/apis/realtime/graphql-subscriptions/)
- [WebTransport](https://apis.io/apis/realtime/webtransport/)
- [Ably](https://apis.io/apis/realtime/ably/)
- [PubNub](https://apis.io/apis/realtime/pubnub/)
- [Pusher](https://apis.io/apis/realtime/pusher/)
- [LiveKit](https://apis.io/apis/realtime/livekit/)
- [Daily](https://apis.io/apis/realtime/daily/)

## Tags

SSE, Server-Sent Events, Protocol, Unidirectional, Standard

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/realtime/server-sent-events/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/realtime/.