---
name: "CURLOPT_HTTP09_ALLOWED"
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_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

0

## PROTOCOLS

This functionality affects http only

## 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_HTTP09_ALLOWED, 1L);
    result = curl_easy_perform(curl);
  }
}
```

## HISTORY

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.

## AVAILABILITY

Added in curl 7.64.0

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