cowboy_req:set_resp_header - Set a response header


set_resp_header(Name, Value, Req :: cowboy_req:req())
	-> Req

Name  :: binary()  %% lowercase; case insensitive
Value :: iodata()  %% case depends on header

Set a header to be sent with the response.

The header name must be given as a lowercase binary string. While header names are case insensitive, Cowboy requires them to be given as lowercase to function properly.

Cowboy does not allow duplicate header names. Headers set by this function may be overwritten by those set from the reply functions.

Use cowboy_req:set_resp_cookie(3) instead of this function to set cookies.



Header name as a lowercase binary string.


Header value.


The Req object.

Return value

A new Req object is returned.

The returned Req object must be used from that point onward, otherwise the header will not be sent in the response.


  • 1.0: Function introduced.


Set a header in the response
Req = cowboy_req:set_resp_header(<<"allow">>, "GET", Req0).
Construct a header using iolists
Req = cowboy_req:set_resp_header(<<"allow">>,
    [allowed_methods(), ", OPTIONS"], Req0).

See also

cowboy_req(3), cowboy_req:set_resp_cookie(3), cowboy_req:set_resp_headers(3), cowboy_req:has_resp_header(3), cowboy_req:resp_header(3), cowboy_req:resp_headers(3), cowboy_req:delete_resp_header(3), cowboy_req:reply(3), cowboy_req:stream_reply(3)

Cowboy 2.7 Function Reference


Version select

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