Request headers

Request headers are key-value pairs sent along with an HTTP request to provide additional information to the server about the request. The request headers give the server more information about how to process the incoming request.

Default Headers: Default headers are predefined headers that Bruno sends automatically with every request. You do not need to add them yourself, and they are not shown on the Headers tab. To see them on the wire, open the Timeline tab after sending a request.

Bruno sends the following default headers:

Header	Value
User-Agent	bruno-runtime/<version> — the running Bruno app or CLI version.
Accept	application/json, text/plain, */*
Accept-Encoding	gzip, compress, deflate, br
Content-Type	Set automatically based on the request Body type (for example application/json for JSON, application/x-www-form-urlencoded for Form URL Encoded, multipart/form-data for Multipart Form).
Content-Length	Set automatically based on the encoded body size.
Host	Derived from the request URL.

You can override any default header by adding a header with the same name on the Headers tab.

Custom Headers: Custom headers are headers that are user-defined and are not part of the official HTTP specification.

Create request headers in Bruno

1. Create request inside collection.
2. Navigate to the Headers tab.
3. Enter the Name, Value, and an optional Description for each header.
4. Save and execute the request.

To view default headers, navigate to the Headers tab in your request. For custom headers, check the Timeline tab.

Streaming with Server-Sent Events

To work with Server-Sent Events (SSE), set:

Accept: text/event-stream

Bruno keeps the connection open, streams chunks into the response panel live, and swaps the Send button for Cancel while the stream is active. See Server-Sent Events (SSE) for details on cancellation, collection runs, and CLI behavior.