How do I send a HTTP/2 POST request in PHP

The CURL extension for PHP >= 5.5.24 has support for HTTP/2. (since this commit)

You also need a libcurl installed — the underlying library that the curl functions use — with HTTP/2 support enabled. That means a libcurl newer than 7.38.0 but really, the newer the better. Libcurl has to have been built with HTTP/2 support explicitly enabled, using the --with-nghttp2 flag at compile time.

Just use curl as you'd normally use it, and set the CURLOPT_HTTP_VERSION option to use HTTP/2 by passing in CURL_HTTP_VERSION_2_0. Then you'll get the request upgraded to version 2 if the client and server both support it.

Prior to PHP 5.5.24, if libcurl has been built with HTTP/2 support, you can pass in the int value of CURL_HTTP_VERSION_2_0 explicitly as PHP will still pass it through to libcurl. Currently, it has a value of 3 — this should not change, but could.

if (!defined('CURL_HTTP_VERSION_2_0')) {    define('CURL_HTTP_VERSION_2_0', 3);}$ch = curl_init();curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);

Having PHP >= 5.5.24 is not enough to make a HTTP/2 request with curl, even if CURL_HTTP_VERSION_2_0 is defined. You will get an error message like the following if you try to make a request to APNS (Apple Push Notification Service):

?@@?HTTP/2 client preface string missing or corrupt. Hex dump for received bytes: 504f5354202f332f6465766963652f616538666562613534

Since curl is a binding for libcurl, you must also have curl with http/2 enabled.

For a sample code, see my answer to a similar question here on SO

For install procedure, you can follow this tutorial

At the current moment there is no direct HTTP/2 support in PHP.

There is an idea to add such a support in the future direct to PHP:https://wiki.php.net/ideas/php6#http2_support

The 3rd Party library Guzzle https://github.com/guzzle/guzzle supports HTTP/2, if the correct php and curl version are installed:

use GuzzleHttp\Client;$client = new Client();$client->get('https://http2.akamai.com/demo/tile-0.png', [    'version' => 2.0,    'debug' => true,]);