---
name: "CURLOPT_CAINFO"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_CAINFO"
---

# CURLOPT\_CAINFO(3)

path to Certificate Authority (CA) bundle

## NAME

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

## SYNOPSIS

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

## DESCRIPTION

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

If *[CURLOPT\_SSL\_VERIFYPEER(3)](/CURLOPT_SSL_VERIFYPEER/3.md)* is zero and you avoid verifying the server's certificate, *[CURLOPT\_CAINFO(3)](/CURLOPT_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.

(iOS and macOS) When curl uses Secure Transport this option is supported. If the option is not set, then curl uses the certificates in the system and user Keychain to verify the peer.

(Schannel) This option is supported for Schannel in Windows 7 or later but we recommend not using it until Windows 8 since it works better starting then. If the option is not set, then curl uses the certificates in the Windows' store of root certificates (the default for Schannel).

The application does not have to keep the string around after setting this option.

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

## DEFAULT

Built-in system specific. When curl is built with Secure Transport or Schannel, this option is not set by default.

## PROTOCOLS

All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_CAINFO, "/etc/certs/cabundle.pem");
    curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

For the SSL engines that do not support certificate files the *[CURLOPT\_CAINFO(3)](/CURLOPT_CAINFO/3.md)* option is ignored. Schannel support added in libcurl 7.60.

## RETURN VALUE

Returns CURLE\_OK if the option is supported, CURLE\_UNKNOWN\_OPTION if not, or CURLE\_OUT\_OF\_MEMORY if there was insufficient heap space.

## SEE ALSO

[**CURLINFO\_CAINFO**(3)](/CURLINFO_CAINFO/3.md), [**CURLOPT\_CAINFO\_BLOB**(3)](/CURLOPT_CAINFO_BLOB/3.md), [**CURLOPT\_CAPATH**(3)](/CURLOPT_CAPATH/3.md), [**CURLOPT\_CA\_CACHE\_TIMEOUT**(3)](/CURLOPT_CA_CACHE_TIMEOUT/3.md), [**CURLOPT\_SSL\_VERIFYHOST**(3)](/CURLOPT_SSL_VERIFYHOST/3.md), [**CURLOPT\_SSL\_VERIFYPEER**(3)](/CURLOPT_SSL_VERIFYPEER/3.md)