---
name: "CURLOPT_USERAGENT"
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_USERAGENT"
---

# CURLOPT\_USERAGENT(3)

HTTP user-agent header

## NAME

CURLOPT\_USERAGENT - HTTP user-agent header

## SYNOPSIS

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

## DESCRIPTION

Pass a pointer to a null-terminated string as parameter. It is used to set the User-Agent: header field in the HTTP request sent to the remote server. You can also set any custom header with *[CURLOPT\_HTTPHEADER(3)](/CURLOPT_HTTPHEADER/3.md)*.

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

## DEFAULT

NULL, no User-Agent: header is used by default.

## PROTOCOLS

HTTP, HTTPS

## 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_USERAGENT, "Dark Secret Ninja/1.0");
    curl_easy_perform(curl);
  }
}
```

## AVAILABILITY

As long as HTTP is supported

## RETURN VALUE

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

## SEE ALSO

[**CURLOPT\_CUSTOMREQUEST**(3)](/CURLOPT_CUSTOMREQUEST/3.md), [**CURLOPT\_HTTPHEADER**(3)](/CURLOPT_HTTPHEADER/3.md), [**CURLOPT\_REFERER**(3)](/CURLOPT_REFERER/3.md), [**CURLOPT\_REQUEST\_TARGET**(3)](/CURLOPT_REQUEST_TARGET/3.md)