---
name: "CURLOPT_PROXY_CAINFO"
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_PROXY_CAINFO"
---

# CURLOPT\_PROXY\_CAINFO(3)

path to proxy Certificate Authority (CA) bundle

## NAME

CURLOPT\_PROXY\_CAINFO - path to proxy Certificate Authority (CA) bundle

## SYNOPSIS

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

## DESCRIPTION

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

Pass a char pointer to a null-terminated string naming a file holding one or more certificates to verify the HTTPS proxy with.

If *[CURLOPT\_PROXY\_SSL\_VERIFYPEER(3)](/CURLOPT_PROXY_SSL_VERIFYPEER/3.md)* is zero and you avoid verifying the server's certificate, *[CURLOPT\_PROXY\_CAINFO(3)](/CURLOPT_PROXY_CAINFO/3.md)* need not even indicate an accessible file.

This option is by default set to the system path where libcurl's CA certificate bundle is assumed to be stored, as established at build time.

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.

The default value for this can be figured out with *[CURLINFO\_CAINFO(3)](/CURLINFO_CAINFO/3.md)*.

## DEFAULT

Built-in system specific

## PROTOCOLS

This functionality affects  all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. only

All TLS backends support this option.

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    /* using an HTTPS proxy */
    curl_easy_setopt(curl, CURLOPT_PROXY, "https://proxy.example:443");
    curl_easy_setopt(curl, CURLOPT_PROXY_CAINFO, "/etc/certs/cabundle.pem");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## NOTES

For TLS backends that do not support certificate files, the *[CURLOPT\_PROXY\_CAINFO(3)](/CURLOPT_PROXY_CAINFO/3.md)* option is ignored. Refer to https://curl.se/docs/ssl-compared.html

## AVAILABILITY

Added in curl 7.52.0

## 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\_CAINFO**(3)](/CURLOPT_CAINFO/3.md), [**CURLOPT\_CAINFO\_BLOB**(3)](/CURLOPT_CAINFO_BLOB/3.md), [**CURLOPT\_CAPATH**(3)](/CURLOPT_CAPATH/3.md), [**CURLOPT\_PROXY\_CAINFO\_BLOB**(3)](/CURLOPT_PROXY_CAINFO_BLOB/3.md), [**CURLOPT\_PROXY\_CAPATH**(3)](/CURLOPT_PROXY_CAPATH/3.md), [**CURLOPT\_PROXY\_SSL\_VERIFYHOST**(3)](/CURLOPT_PROXY_SSL_VERIFYHOST/3.md), [**CURLOPT\_PROXY\_SSL\_VERIFYPEER**(3)](/CURLOPT_PROXY_SSL_VERIFYPEER/3.md), [**CURLOPT\_SSL\_VERIFYHOST**(3)](/CURLOPT_SSL_VERIFYHOST/3.md), [**CURLOPT\_SSL\_VERIFYPEER**(3)](/CURLOPT_SSL_VERIFYPEER/3.md)