---
name: "CURLOPT_HTTP09_ALLOWED"
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_HTTP09_ALLOWED"
---

# CURLOPT\_HTTP09\_ALLOWED(3)

allow HTTP/0.9 response

## NAME

CURLOPT\_HTTP09\_ALLOWED - allow HTTP/0.9 response

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTP09_ALLOWED, long allowed);
```

## DESCRIPTION

Pass the long argument *allowed* set to 1L to allow HTTP/0.9 responses.

An HTTP/0.9 response is a server response entirely without headers and only a body. You can connect to lots of random TCP services and still get a response that curl might consider to be HTTP/0.9!

## DEFAULT

curl allowed HTTP/0.9 responses by default before 7.66.0

Since 7.66.0, libcurl requires this option set to 1L to allow HTTP/0.9 responses.

## PROTOCOLS

HTTP

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode ret;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_HTTP09_ALLOWED, 1L);
    ret = curl_easy_perform(curl);
  }
}
```

## AVAILABILITY

Option added in 7.64.0, present along with HTTP.

## RETURN VALUE

Returns CURLE\_OK if HTTP is supported, and CURLE\_UNKNOWN\_OPTION if not.

## SEE ALSO

[**CURLOPT\_HTTP\_VERSION**(3)](/CURLOPT_HTTP_VERSION/3.md), [**CURLOPT\_SSLVERSION**(3)](/CURLOPT_SSLVERSION/3.md)