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FastAPI · Class

ServerSentEvent

FastAPI can stream Server-Sent Events over HTTP with EventSourceResponse. Yield plain values for JSON data, or ServerSentEvent objects for event metadata and raw text.

Last updated

Since
0.135.0

Syntax

@app.get("/events", response_class=EventSourceResponse)
async def events() -> AsyncIterable[ServerSentEvent]:
    yield ServerSentEvent(data={"ok": True})

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Subscribe
  • EventSourceResponse
  • ServerSentEvent
  • Stream JSON Lines
  • Last-Event-ID
  • text/event-stream

Source: Server-Sent Events (SSE) - FastAPI. Checked 2026-11-03.