.\" generated by cd2nroff 0.1 from CURLOPT_CERTINFO.md
.TH CURLOPT_CERTINFO 3 "2026-09-02" libcurl
.SH NAME
CURLOPT_CERTINFO \- request SSL certificate information
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CERTINFO, long certinfo);
.fi
.SH DESCRIPTION
Pass a long set to 1 to enable libcurl\(aqs certificate chain info gatherer. With
this enabled, libcurl extracts lots of information and data about the
certificates in the certificate chain used in the SSL connection. This data
may then be retrieved after a transfer using \fIcurl_easy_getinfo(3)\fP and
its option \fICURLINFO_CERTINFO(3)\fP.
.SH DEFAULT
0
.SH PROTOCOLS
This functionality affects  all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. only

This option works only with the following TLS backends:
GnuTLS, OpenSSL, Rustls and Schannel
.SH EXAMPLE
.nf
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://www.example.com/");

    /* 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);

    result = curl_easy_perform(curl);

    if(result == CURLE_OK) {
      struct curl_certinfo *ci;
      result = curl_easy_getinfo(curl, CURLINFO_CERTINFO, &ci);

      if(result == CURLE_OK) {
        int i;
        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);
        }
      }
    }
    curl_easy_cleanup(curl);
  }
}
.fi
.SH HISTORY
Schannel support added in 7.50.0. mbedTLS support added in 8.9.0.
.SH AVAILABILITY
Added in curl 7.19.1
.SH RETURN VALUE
\fIcurl_easy_setopt(3)\fP returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non\-zero means an error occurred, see
\fIlibcurl\-errors(3)\fP.
.SH SEE ALSO
.BR CURLINFO_CAINFO (3),
.BR CURLINFO_CAPATH (3),
.BR CURLINFO_CERTINFO (3),
.BR CURLOPT_CAINFO (3),
.BR CURLOPT_SSL_VERIFYPEER (3)