<?php
if ($handle = opendir(dirname(__FILE__))) {
    echo '<ul>';
    while (false !== ($name = readdir($handle))) {
        if ($name != '.' && $name != '..') {
            if (substr($name, -5) == '.json') {
                echo '<li>' . $name . '</li>';
            }
        }
    }
    echo '</ul>';
}