$kirby->url('index')
Returns the base url of the site
Example
<?= $kirby->url('index') ?>Custom setup
If you want to overwrite the Url you can do this in your index.php by passing a custom Url setup to the Kirby constructor.
<?php
include 'kirby/bootstrap.php';
$kirby = new Kirby([
    'urls' => [
        'index' => 'https://example.com/custom/url',
    ],
]);
echo $kirby->render();