CURLINFO_HEADER_SIZE - get size of retrieved headers

Added in curl 7.4.1

Pass a pointer to a long to receive the total size of all the headers received. Measured in number of bytes. The total includes the size of any received headers suppressed by CURLOPT_SUPPRESS_CONNECT_HEADERS(3).

int main(void) { CURL *curl = curl_easy_init(); if(curl) { CURLcode res; curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); res = curl_easy_perform(curl); if(res == CURLE_OK) { long size; res = curl_easy_getinfo(curl, CURLINFO_HEADER_SIZE, &size); if(!res) printf("Header size: %ld bytes\n", size); } curl_easy_cleanup(curl); } }

CURLINFO_HEADER_SIZE - get size of retrieved headers

This functionality affects all supported protocols

curl_easy_getinfo(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).

CURLINFO_REQUEST_SIZE(3), CURLINFO_SIZE_DOWNLOAD(3), curl_easy_getinfo(3), curl_easy_setopt(3) libcurl 2025-06-16 CURLINFO_HEADER_SIZE(3)

#include <curl/curl.h> CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_HEADER_SIZE, long *sizep);