CURLOPT_TCP_NODELAY - the TCP_NODELAY option

Added in curl 7.11.2

1

Pass a long specifying whether the TCP_NODELAY option is to be set or cleared (1L = set, 0 = clear). The option is set by default. This has no effect after the connection has been established. Setting this option to 1L disables the Nagle algorithm on connections created using this handle. The purpose of this algorithm is to minimize the number of small packets on the network (where "small packets" means TCP segments less than the Maximum Segment Size for the network). Maximizing the amount of data sent per TCP segment is good because it amortizes the overhead of the send. However, in some cases small segments may need to be sent without delay. This is less efficient than sending larger amounts of data at a time, and can contribute to congestion on the network if overdone.

int main(void) { CURL *curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); /* leave Nagle enabled */ curl_easy_setopt(curl, CURLOPT_TCP_NODELAY, 0L); curl_easy_perform(curl); } }

The default was changed to 1 from 0 in 7.50.2.

CURLOPT_TCP_NODELAY - the TCP_NODELAY option

This functionality affects tcp only

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_BUFFERSIZE(3), CURLOPT_SOCKOPTFUNCTION(3), CURLOPT_TCP_KEEPALIVE(3) libcurl 2025-06-16 CURLOPT_TCP_NODELAY(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TCP_NODELAY, long nodelay);