.htaccess

<IfModule mod_rewrite.c>

    RewriteEngine On
    RewriteBase /

    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule .* /passgen/index.php  [L,QSA]

</IfModule>

index.php

<?php

/**
 * Generate a Password
 */
class PassGen
{

    /**
     * Constructor
     */
    public function __construct()
    {
        $basePath = basename(__DIR__);

        $uri = filter_input(INPUT_SERVER, 'REQUEST_URI');
        $uri = trim(str_replace("/$basePath", "", $uri), '/');

        if (empty($uri)) {
            echo $this->instructions();
            return;
        }

        $options = explode('/', $uri);

        $length = null;
        $numbers = true;
        $uppercase = true;
        $lowercase = true;
        $othercharsArr = array();

        foreach ($options as $option) {
            if (is_numeric($option) && is_null($length)) {
                $length = intval($option);
                continue;
            }
            if ($option === '!nums') {
                $numbers = false;
                continue;
            }
            if ($option === '!uc') {
                $uppercase = false;
                continue;
            }
            if ($option === '!lc') {
                $lowercase = false;
                continue;
            }
            array_push($othercharsArr, $option);
        }

        $otherchars = implode('', $othercharsArr);

        if (is_null($length)) {
            $length = 8;
        }

        echo self::GeneratePassword($length, $numbers, $uppercase, $lowercase, $otherchars);
    }

    /**
    * Print the usage instructions
    */
    protected function instructions()
    {
        $host = filter_input(INPUT_SERVER, 'HTTP_HOST');
        $basePath = basename(__DIR__);

        $chars = urlencode('!@#$%^&*()_+-=');

        return <<<EOI
<pre>
/**
 * Generate a password of the given length using a simple url
 *
 * Use any of the following options in any order to generate a password.
 * Ommitting all options will show this usage guide.
 *
 * http://$host/$basePath/[length]/!uc/!lc/!nums/[other]
 * [length]     : length of password as a numeric value
 * !uc          : no upper case characters
 * !lc          : no lower case characters
 * !nums        : no numbers
 * [other]      : other allowed characters
 *
 * Samples:
 * <a href="http://$host/$basePath/12/{$this->encode('!@#$%^&*()_+-=')}">http://$host/$basePath/12/!@#$%^&*()_+-=</a> - 12 character including [a-Z0-9!@#$%^&*()_+-=]
 * <a href="http://$host/$basePath/20/!lc">http://$host/$basePath/12/!lc</a> - 20 character including [A-Z0-9]
 * <a href="http://$host/$basePath/64/!lc/!uc/ABCDEF">http://$host/$basePath/64/!lc/!uc/ABCDEF</a> - 64 character including [A-F0-9]
 * <a href="http://$host/$basePath/32/!lc/!uc/ABCDEF">http://$host/$basePath/32/!lc/!uc/ABCDEF</a> - 32 character including [A-F0-9]
 * <a href="http://$host/$basePath/64">http://$host/$basePath/64</a> - 64 character including [a-Z0-9]
 * <a href="http://$host/$basePath/32">http://$host/$basePath/32</a> - 32 character including [a-Z0-9]
 */
</pre>
EOI;
    }

    /**
    * local shortcut to urlencode;
    */
    protected function encode($str)
    {
        return urlencode($str);
    }

    /**
    * Generate a random password.
    *
    * @param integer $length
    * @param boolean $numbers
    * @param boolean $uppercase
    * @param boolean $lowercase
    * @param string $otherchars
    * @return string
    */
    public static function GeneratePassword($length = 8, $numbers = true, $uppercase = true, $lowercase = true, $otherchars = '') {
        $charlist = '';

        if ($numbers) {
            $charlist .= '0123456789';
        }

        if ($uppercase) {
            $charlist .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
        }

        if ($lowercase) {
            $charlist .= 'abcdefghijklmnopqrstuvwxyz';
        }

        if ($otherchars) {
            $charlist .= $otherchars;
        }

        $generated = '';

        if (is_numeric($length) && $length > 0) {
            $charlistLength = strlen($charlist);
            if ($charlistLength > 0) {
                for ($i = 0; $i < $length; $i++) {
                    $randomIndex = rand(0, $charlistLength - 1);
                    $generated .= substr($charlist, $randomIndex, 1);
                }
                return $generated;
            } else {
                trigger_error('Attempting to generate a password with no allowed characters.', E_USER_ERROR);
            }
        } else {
            trigger_error('Invalid length specified for password. Length must be a numeric value greater than 0.', E_USER_ERROR);
        }
    }

    /**
     * Destructor
     */
    public function __destruct()
    {
        // insert code here.
    }
}

new PassGen;