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CURLOPT_ACCEPT_ENCODING(3) Library Functions Manual CURLOPT_ACCEPT_ENCODING(3)

NAME
       CURLOPT_ACCEPT_ENCODING - automatic decompression of HTTP downloads

SYNOPSIS
       #include	<curl/curl.h>

       CURLcode	curl_easy_setopt(CURL *handle, CURLOPT_ACCEPT_ENCODING,	char *enc);

DESCRIPTION
       Pass a char pointer argument specifying what encoding you would like.

       Sets  the  contents  of the Accept-Encoding: header sent	in an HTTP re-
       quest, and enables decoding of  a  response  when  a  Content-Encoding:
       header is received.

       libcurl potentially supports several different compressed encodings de-
       pending on what support that has	been built-in.

       To aid applications not having to bother	about what specific algorithms
       this  particular	 libcurl  build	supports, libcurl allows a zero-length
       string to be set	("") to	ask for	an Accept-Encoding: header to be  used
       that contains all built-in supported encodings.

       Alternatively,  you  can	specify	exactly	the encoding or	list of	encod-
       ings you	want in	the response. The following encodings  are  supported:
       identity,  meaning non-compressed, deflate which	requests the server to
       compress	its response using the zlib algorithm, gzip which requests the
       gzip algorithm, (since curl 7.57.0) br which is brotli and (since  curl
       7.72.0) zstd which is zstd. Provide them	in the string as a comma-sepa-
       rated list of accepted encodings, like: "br, gzip, deflate".

       Set  CURLOPT_ACCEPT_ENCODING(3) to NULL to explicitly disable it, which
       makes libcurl not send an Accept-Encoding: header  and  not  decompress
       received	contents automatically.

       You can also opt	to include the Accept-Encoding:	header in your request
       with CURLOPT_HTTPHEADER(3) but then there is no automatic decompressing
       when receiving data.

       Setting	this  option is	a request, not an order; the server may	or may
       not do it. It must be set (to any non-NULL value) or else any  encoding
       done by the server is ignored.

       Servers might respond with Content-Encoding: even without getting a Ac-
       cept-Encoding:  in  the request.	Servers	might respond with a different
       content encoding	than what was asked for	in the request.

       The Content-Length: header field	servers	send for a compressed response
       is supposed to indicate the length of the compressed  content  so  when
       auto  decoding is enabled it may	not match the sum of bytes reported by
       the write callbacks (although, sending the length of the	non-compressed
       content is a common server mistake).

       The application does not	have to	keep the string	around	after  setting
       this option.

       Using this option multiple times	makes the last set string override the
       previous	ones.

       WARNING:	when decompressing data, even tiny transfers might be expanded
       and generate a huge amount of bytes. You	might want to limit using this
       option  to only known and trusted sites using secure protocols, perhaps
       in combination with CURLOPT_MAXFILESIZE_LARGE(3).

HISTORY
       This option was called CURLOPT_ENCODING before 7.21.6

NOTES
       The specific libcurl you	are using must have been built with zlib to be
       able to decompress gzip and deflate responses, with the brotli  library
       to  decompress brotli responses and with	the zstd library to decompress
       zstd responses.

DEFAULT
       NULL

PROTOCOLS
       This functionality affects http only

EXAMPLE
       int main(void)
       {
	 CURL *curl = curl_easy_init();
	 if(curl) {
	   CURLcode result;
	   curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

	   /* enable all supported built-in compressions */
	   curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "");

	   /* Perform the request */
	   result = curl_easy_perform(curl);
	   curl_easy_cleanup(curl);
	 }
       }

AVAILABILITY
       Added in	curl 7.21.6

RETURN VALUE
       curl_easy_setopt(3) returns a CURLcode indicating success or error.

       CURLE_OK	(0) means everything was OK, non-zero means an error occurred,
       see libcurl-errors(3).

SEE ALSO
       CURLOPT_HTTPHEADER(3), CURLOPT_HTTP_CONTENT_DECODING(3),	CURLOPT_TRANS-
       FER_ENCODING(3)

libcurl				  2026-06-11	    CURLOPT_ACCEPT_ENCODING(3)

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