$server = 'http://thumbor.example.com:1234';
$secret = 'my-secret-key';

echo Thumbor\Url\Builder::construct($server, $secret, 'http://images.example.com/llamas.jpg')
    ->fitIn(640, 480)
    ->addFilter('fill', 'green');

// => http://thumbor.example.com:1234/OFDRoURwi9WVbZNfeOJVfIKr1Js=/fit-in/640x480/filters:fill(green)/http://images/example.com/llamas.jpg

$thumbnailUrlFactory = Thumbor\Url\BuilderFactory::construct($server, $secret);

echo $thumbnailUrlFactory
    ->url('http://images.example.com/llamas.jpg')
    ->fitIn(640, 480)
    ->addFilter('fill', 'green');

echo $thumbnailUrlFactory
    ->url('http://images.example.com/butts.png')
    ->crop(20, 20, 300, 300)
    ->valign('middle');

// etc