get the TLS certificate chain


#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_CERTINFO,
                           struct curl_certinfo **chainp);


Pass a pointer to a struct curl_certinfo * and you will get it set to point to a struct that holds a number of linked lists with info about the certificate chain, assuming you had CURLOPT_CERTINFO(3) enabled when the request was made. The struct reports how many certs it found and then you can extract info for each of those certs by following the linked lists. The info chain is provided in a series of data in the format "name:content" where the content is for the specific named data. See also the certinfo.c example.


All TLS-based


curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "");

  /* connect to any HTTPS site, trusted or not */
  curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
  curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);

  curl_easy_setopt(curl, CURLOPT_CERTINFO, 1L);

  res = curl_easy_perform(curl);

  if (!res) {
    struct curl_certinfo *ci;
    res = curl_easy_getinfo(curl, CURLINFO_CERTINFO, &ci);

    if (!res) {
      printf("%d certs!\n", ci->num_of_certs);

      for(i = 0; i < ci->num_of_certs; i++) {
        struct curl_slist *slist;

        for(slist = ci->certinfo[i]; slist; slist = slist->next)
          printf("%s\n", slist->data);


This option is only working in libcurl built with OpenSSL, NSS, Schannel, GSKit or Secure Transport support. Schannel support added in 7.50.0. Secure Transport support added in 7.79.0.

Added in 7.19.1

Return Value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

See Also

curl_easy_getinfo(3), curl_easy_setopt(3),

Referenced By

curl_easy_getinfo(3), CURLOPT_CERTINFO(3).

April 26, 2023 libcurl 8.1.1