---
name: "CURLOPT_SSL_FALSESTART"
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_SSL_FALSESTART"
---

# CURLOPT\_SSL\_FALSESTART(3)

TLS false start

## NAME

CURLOPT\_SSL\_FALSESTART - TLS false start

## SYNOPSIS

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

## DESCRIPTION

Pass a long as parameter set to 1L to enable or 0 to disable.

This option determines whether libcurl should use false start during the TLS handshake. False start is a mode where a TLS client starts sending application data before verifying the server's Finished message, thus saving a round trip when performing a full handshake.

## DEFAULT

0

## PROTOCOLS

This functionality affects  all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. only

No TLS backend supports this option.

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

## DEPRECATED

Deprecated since 8.15.0.

## AVAILABILITY

Added in curl 7.42.0

## 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\_TCP\_FASTOPEN**(3)](/CURLOPT_TCP_FASTOPEN/3.md)