trailing slash for a php web service

I'm new in webservice and I created a little example.

The code is:

$json_encoded = file_get_contents('php://input');
$array = json_decode($json_encoded, true);
if ( count($array) ) {
   echo "OK: data received";
} else {
   echo "NO data received";
}

This little script is located at http://www.example.com/api/check/index.php

Now if I try to use POSTMAN software to test it wth a json payload, it works great if I use a POST call at http://www.example.com/api/check/ :

OK: data received

But if I try to send a request to the same address without trailing slash http://www.example.com/api/check i get:

NO data received

Is there a way to get it working for both calls (with and without trailing slash) ?

I cannot edit server config, so i'd like to get it working editing index.php or adding an .htaccess here http://www.example.com/api/check/

Any suggest?