CURLOPT\_PROXY\_SSLCERT(3) Library Functions Manual CURLOPT\_PROXY\_SSLCERT(3)

# [NAME](#NAME)

CURLOPT\_PROXY\_SSLCERT - HTTPS proxy client certificate

# [SYNOPSIS](#SYNOPSIS)

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

# [DESCRIPTION](#DESCRIPTION)

This option is for connecting to an HTTPS proxy, not an HTTPS server.

Pass a pointer to a null-terminated string as parameter. The string should be the filename of your client certificate used to connect to the HTTPS proxy. The default format "PEM", and can be changed with [*CURLOPT\_PROXY\_SSLCERTTYPE(3)*](/man/os/curl/CURLOPT_PROXY_SSLCERTTYPE.3).

When using a client certificate, you most likely also need to provide a private key with [*CURLOPT\_PROXY\_SSLKEY(3)*](/man/os/curl/CURLOPT_PROXY_SSLKEY.3).

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 to disable its use again.

# [DEFAULT](#DEFAULT)

NULL

# [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, Schannel, mbedTLS and wolfSSL

# [EXAMPLE](#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_PROXY, "https://proxy.example");


    curl_easy_setopt(curl, CURLOPT_PROXY_SSLCERT, "client.pem");


    curl_easy_setopt(curl, CURLOPT_PROXY_SSLKEY, "key.pem");


    curl_easy_setopt(curl, CURLOPT_PROXY_KEYPASSWD, "s3cret");


    result = curl_easy_perform(curl);


    curl_easy_cleanup(curl);


  }
}
```

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.52.0

# [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)

[**CURLOPT\_PROXY\_SSLCERTTYPE**(3)](/man/os/curl/CURLOPT_PROXY_SSLCERTTYPE.3), [**CURLOPT\_PROXY\_SSLKEY**(3)](/man/os/curl/CURLOPT_PROXY_SSLKEY.3), [**CURLOPT\_SSLCERT**(3)](/man/os/curl/CURLOPT_SSLCERT.3)

2026-10-22 libcurl

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Document: CURLOPT_PROXY_SSLCERT(3) from curl 8.23.0-r2 (Chainguard OS)
Source: https://github.com/curl/curl.git