CURLOPT\_POST(3) Library Functions Manual CURLOPT\_POST(3)

# [NAME](#NAME)

CURLOPT\_POST - make an HTTP POST

# [SYNOPSIS](#SYNOPSIS)

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

# [DESCRIPTION](#DESCRIPTION)

A parameter set to 1 tells libcurl to do a regular HTTP post. This also makes libcurl use a "Content-Type: application/x-www-form-urlencoded" header. This is the most commonly used POST method.

Use one of [*CURLOPT\_POSTFIELDS(3)*](/man/os/curl/CURLOPT_POSTFIELDS.3) or [*CURLOPT\_COPYPOSTFIELDS(3)*](/man/os/curl/CURLOPT_COPYPOSTFIELDS.3) options to specify what data to post and [*CURLOPT\_POSTFIELDSIZE(3)*](/man/os/curl/CURLOPT_POSTFIELDSIZE.3) or [*CURLOPT\_POSTFIELDSIZE\_LARGE(3)*](/man/os/curl/CURLOPT_POSTFIELDSIZE_LARGE.3) to set the data size.

Optionally, you can provide data to POST using the [*CURLOPT\_READFUNCTION(3)*](/man/os/curl/CURLOPT_READFUNCTION.3) and [*CURLOPT\_READDATA(3)*](/man/os/curl/CURLOPT_READDATA.3) options but then you must make sure to not set [*CURLOPT\_POSTFIELDS(3)*](/man/os/curl/CURLOPT_POSTFIELDS.3) to anything but NULL. When providing data with a callback, you must transmit it using chunked transfer-encoding or you must set the size of the data with the [*CURLOPT\_POSTFIELDSIZE(3)*](/man/os/curl/CURLOPT_POSTFIELDSIZE.3) or [*CURLOPT\_POSTFIELDSIZE\_LARGE(3)*](/man/os/curl/CURLOPT_POSTFIELDSIZE_LARGE.3) options. To enable chunked encoding, pass in the appropriate Transfer-Encoding header, see the post-callback.c example.

You can override the default POST Content-Type: header by setting your own with [*CURLOPT\_HTTPHEADER(3)*](/man/os/curl/CURLOPT_HTTPHEADER.3).

Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with [*CURLOPT\_HTTPHEADER(3)*](/man/os/curl/CURLOPT_HTTPHEADER.3) as usual.

If you use POST to an HTTP 1.1 server, you can send data without knowing the size before starting the POST if you use chunked encoding. You enable this by adding a header like "Transfer-Encoding: chunked" with [*CURLOPT\_HTTPHEADER(3)*](/man/os/curl/CURLOPT_HTTPHEADER.3). With HTTP 1.0 or without chunked transfer, you must specify the size in the request. libcurl automatically uses chunked encoding for POSTs if the size is unknown.

When setting [*CURLOPT\_POST(3)*](/man/os/curl/CURLOPT_POST.3) to 1, libcurl automatically sets [*CURLOPT\_NOBODY(3)*](/man/os/curl/CURLOPT_NOBODY.3) and [*CURLOPT\_HTTPGET(3)*](/man/os/curl/CURLOPT_HTTPGET.3) to 0.

If you issue a POST request and then want to make a HEAD or GET using the same reused handle, you must explicitly set the new request type using [*CURLOPT\_NOBODY(3)*](/man/os/curl/CURLOPT_NOBODY.3) or [*CURLOPT\_HTTPGET(3)*](/man/os/curl/CURLOPT_HTTPGET.3) or similar.

When setting [*CURLOPT\_POST(3)*](/man/os/curl/CURLOPT_POST.3) to 0, libcurl resets the request type to the default to disable the POST. Typically that means gets reset to GET. Instead you should set a new request type explicitly as described above.

# [DEFAULT](#DEFAULT)

0, disabled

# [PROTOCOLS](#PROTOCOLS)

This functionality affects http only

# [EXAMPLE](#EXAMPLE)

```
int main(void)
{


  CURL *curl = curl_easy_init();


  if(curl) {


    CURLcode result;


    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");


    curl_easy_setopt(curl, CURLOPT_POST, 1L);


    /* set up the read callback with CURLOPT_READFUNCTION */


    result = curl_easy_perform(curl);


    curl_easy_cleanup(curl);


  }
}
```

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.1

# [RETURN VALUE](#RETURN_VALUE)

[*curl\_easy\_setopt(3)*](/man/os/curl/curl_easy_setopt.3) returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see [*libcurl-errors(3)*](/man/os/curl/libcurl-errors.3).

# [SEE ALSO](#SEE_ALSO)

[**CURLOPT\_HTTPPOST**(3)](/man/os/curl/CURLOPT_HTTPPOST.3), [**CURLOPT\_POSTFIELDS**(3)](/man/os/curl/CURLOPT_POSTFIELDS.3), [**CURLOPT\_UPLOAD**(3)](/man/os/curl/CURLOPT_UPLOAD.3)

2026-10-22 libcurl

---

Document: CURLOPT_POST(3) from curl 8.23.0-r2 (Chainguard OS)
Source: https://github.com/curl/curl.git