CURLOPT\_CERTINFO(3) Library Functions Manual CURLOPT\_CERTINFO(3)

# [NAME](#NAME)

CURLOPT\_CERTINFO - request SSL certificate information

# [SYNOPSIS](#SYNOPSIS)

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CERTINFO, long certinfo);
```

# [DESCRIPTION](#DESCRIPTION)

Pass a long set to 1 to enable libcurl's 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 [*curl\_easy\_getinfo(3)*](/man/os/curl/curl_easy_getinfo.3) and its option [*CURLINFO\_CERTINFO(3)*](/man/os/curl/CURLINFO_CERTINFO.3).

# [DEFAULT](#DEFAULT)

0

# [PROTOCOLS](#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

# [EXAMPLE](#EXAMPLE)

```
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);


  }
}
```

# [HISTORY](#HISTORY)

Schannel support added in 7.50.0. mbedTLS support added in 8.9.0.

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.19.1

# [RETURN VALUE](#RETURN_VALUE)

[*curl\_easy\_setopt(3)*](/man/os/curl/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)*](/man/os/curl/libcurl-errors.3).

# [SEE ALSO](#SEE_ALSO)

[**CURLINFO\_CAINFO**(3)](/man/os/curl/CURLINFO_CAINFO.3), [**CURLINFO\_CAPATH**(3)](/man/os/curl/CURLINFO_CAPATH.3), [**CURLINFO\_CERTINFO**(3)](/man/os/curl/CURLINFO_CERTINFO.3), [**CURLOPT\_CAINFO**(3)](/man/os/curl/CURLOPT_CAINFO.3), [**CURLOPT\_SSL\_VERIFYPEER**(3)](/man/os/curl/CURLOPT_SSL_VERIFYPEER.3)

2026-10-01 libcurl

---

Document: CURLOPT_CERTINFO(3) from curl 8.22.0-r4 (Chainguard OS)
Source: https://github.com/curl/curl.git