is there a way to disable it?
Yes, you only need to use the JSON_UNESCAPED_SLASHES flag (PHP 5.4+).
!important read before: https://stackoverflow.com/a/10210367/367456 (know what you’re dealing with – know your enemy: DO NOT USE in web/html context – CLI, unless CGI, might be fine thought, if they think they need it in JSON HTTP context for readability purposes, they have a different problem)
json_encode($str, JSON_UNESCAPED_SLASHES);
If you don’t have PHP 5.4 at hand (you certainly already asserted the warning above), pick one of the many existing functions and modify them to your needs, e.g. http://snippets.dzone.com/posts/show/7487 (archived copy).
Example Demo
<?php
/*
* Escaping the reverse-solidus character ("/", slash) is optional in JSON.
*
* This can be controlled with the JSON_UNESCAPED_SLASHES flag constant in PHP.
*
* @link http://stackoverflow.com/a/10210433/367456
*/
$url="http://www.example.com/";
echo json_encode($url), "\n";
echo json_encode($url, JSON_UNESCAPED_SLASHES), "\n";
Example Output:
"http:\/\/www.example.com\/"
"http://www.example.com/"