Generates valid UUID v4 in PHP.

uuid.php

<?php

function uuid() {
	$data    = random_bytes(16);
	$data[6] = chr((ord($data[6]) | 0xC0) & 0x4F);
	$data[8] = chr((ord($data[8]) | 0xC0) & 0xBF);

	$str = bin2hex($str);
	return sprintf('%s-%s-%s-%s-%s', substr($str, 0, 8), substr($str, 8, 4), substr($str, 12, 4), substr($str, 16, 4), substr($str, 20));
}