CURLOPT_POST(3) Introduction to Library Functions CURLOPT_POST(3)
CURLOPT_POST - make an HTTP POST
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_POST, long post);
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) or CURLOPT_COPYPOSTFIELDS(3) options
to specify what data to post and CURLOPT_POSTFIELDSIZE(3) or
CURLOPT_POSTFIELDSIZE_LARGE(3) to set the data size.
Optionally, you can provide data to POST using the
CURLOPT_READFUNCTION(3) and CURLOPT_READDATA(3) options but then you
must make sure to not set 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) or 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).
Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue"
header. You can disable this header with 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). 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) to 1, libcurl automatically sets
CURLOPT_NOBODY(3) and 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) or CURLOPT_HTTPGET(3) or similar.
When setting 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.
0, disabled
This functionality affects http only
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);
}
}
Added in curl 7.1
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).
CURLOPT_HTTPPOST(3), CURLOPT_POSTFIELDS(3), CURLOPT_UPLOAD(3)
libcurl 2026-03-11 CURLOPT_POST(3)
NAME
CURLOPT_POST - make an HTTP POST
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_POST, long post);
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) or CURLOPT_COPYPOSTFIELDS(3) options
to specify what data to post and CURLOPT_POSTFIELDSIZE(3) or
CURLOPT_POSTFIELDSIZE_LARGE(3) to set the data size.
Optionally, you can provide data to POST using the
CURLOPT_READFUNCTION(3) and CURLOPT_READDATA(3) options but then you
must make sure to not set 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) or 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).
Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue"
header. You can disable this header with 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). 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) to 1, libcurl automatically sets
CURLOPT_NOBODY(3) and 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) or CURLOPT_HTTPGET(3) or similar.
When setting 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
0, disabled
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/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
Added in curl 7.1
RETURN VALUE
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).
SEE ALSO
CURLOPT_HTTPPOST(3), CURLOPT_POSTFIELDS(3), CURLOPT_UPLOAD(3)
libcurl 2026-03-11 CURLOPT_POST(3)