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Server-Sent Events (SSE)

Bruno supports Server-Sent Events (SSE) for REST requests. When a request expects a streamed response (Accept: text/event-stream), Bruno keeps the connection open and appends incoming data to the response panel in real time instead of hanging until the stream ends.

Use SSE to test and debug real-time APIs such as OpenAI-style streams, live event feeds, and other long-lived HTTP connections where the server pushes data continuously.

What are Server-Sent Events?

Server-Sent Events are a standard way for a server to push updates to a client over a single HTTP connection. Unlike WebSockets, SSE is unidirectional: the server streams data to the client.

Feature Regular HTTP SSE
Connection Closes after one response Stays open while the stream is active
Data flow One response body Continuous event chunks
Typical use CRUD APIs Live updates, AI token streams, event feeds
Client control Wait for completion Cancel anytime while streaming

How to send an SSE request

  1. Create or open an HTTP request in your collection.
  2. Set the method and URL for your streaming endpoint (for example, a chat completions or events URL).
  3. Open the Headers tab and add:
Name Value
Accept text/event-stream
  1. Click Send (or press ⌘ Enter / Ctrl Enter).

{/* screenshot: SSE request with Accept header and live response panel */}

Bruno detects the streamed response, keeps the connection open, and starts appending chunks to the Response panel as they arrive.

Streaming response behavior

While a stream is active:

  • Incoming data is concatenated and shown live in the response body.
  • The Send (→) button switches to a Cancel button.
  • Elapsed time continues updating for as long as the stream stays open.
  • The stream state resets when the server closes the connection or you cancel it.

Cancel an active stream

  1. While data is streaming, click the Cancel button in the URL bar (where Send normally appears).
  2. Bruno stops receiving new data, closes the connection, and resets the stream state.
  3. The response panel keeps the data received up to the cancellation point.
  4. The button returns to Send so you can run the request again.

Clicking Cancel cancels only the active stream for that request. It does not close other tabs or stop unrelated requests.

Collection runs and CLI

Long-lived SSE connections would block a collection run indefinitely. To keep runners reliable:

  • Collection Runner skips requests that use Accept: text/event-stream.
  • Bruno CLI also skips those requests during bru run.

Test SSE requests individually from the request tab. Use the Collection Runner or CLI for non-streaming requests in the same collection.

If a collection run appears to skip a request unexpectedly, check whether that request sets Accept: text/event-stream. Remove or disable the header for automated runs when you need the request to execute.

Example use cases

  • AI / LLM APIs - Inspect token-by-token or chunked completion streams.
  • Live event feeds - Watch notifications or status updates as the server pushes them.
  • Long-lived monitoring endpoints - Debug keep-alive streams without waiting for a final close.

Tips

  • Prefer an explicit Accept: text/event-stream header so Bruno treats the request as a stream.
  • Use Cancel to stop noisy or endless streams while debugging.
  • Keep SSE requests out of CI collection runs, or tag/structure them so automated runs only execute finite HTTP requests.
  • For bidirectional real-time protocols, use WebSocket instead of SSE.