---
name: "CURLOPT_SSLCERTTYPE"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_SSLCERTTYPE"
---

# CURLOPT\_SSLCERTTYPE(3)

type of client SSL certificate

## NAME

CURLOPT\_SSLCERTTYPE - type of client SSL certificate

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLCERTTYPE, char *type);
```

## DESCRIPTION

Pass a pointer to a null-terminated string as parameter. The string should be the format of your certificate.

Supported formats are "PEM" and "DER", except with Schannel. OpenSSL and Schannel support "P12" for PKCS#12-encoded files. GnuTLS supports P12 starting with curl 8.11.0.

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. Set it to NULL restores back to internal default.

## DEFAULT

"PEM"

## 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, Schannel, mbedTLS and wolfSSL

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_SSLCERT, "client.pem");
    curl_easy_setopt(curl, CURLOPT_SSLCERTTYPE, "PEM");
    curl_easy_setopt(curl, CURLOPT_SSLKEY, "key.pem");
    curl_easy_setopt(curl, CURLOPT_KEYPASSWD, "s3cret");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

Added in curl 7.9.3

## RETURN VALUE

*[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)* returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see *[libcurl-errors(3)](/libcurl-errors/3.md)*.

## SEE ALSO

[**CURLOPT\_SSLCERT**(3)](/CURLOPT_SSLCERT/3.md), [**CURLOPT\_SSLKEY**(3)](/CURLOPT_SSLKEY/3.md)